以稀有、稀散和稀土元素为主体的战略性关键金属矿产资源在新材料、新能源和信息技术等新兴产业具有不可替代的重大用途。近年来,美欧等发达经济体先后制定了各自的关键矿产资源发展战略[1]。随着全球对稀有金属(Li,Ga,Ge及REE)需求日益增加,煤中微量元素引起了国内外学者广泛的关注[2-11]。多个煤田被发现煤中富集微量元素[12-16]。赵存良[17]对邯邢煤田煤中伴生矿产及微量元素进行了研究,认为煤中微量元素特征受陆源及沉积环境的共同影响。代世峰等[18]分析了岩浆侵入对峰峰-邯郸煤田晚古生代煤的岩石学、矿物学和地球化学的影响,利用元素含量随煤级和矿物学亲和力的变化将煤中的元素分为6组,讨论了其来源和赋存状态。前人的研究成果为本文研究的开展提供了基础。
河北峰峰矿区山西组以三角洲沉积体系为主,成煤后,由于燕山期岩浆的侵入作用,导致矿区内煤层的煤类煤质存在差异。笔者以峰峰矿区南部的梧桐庄矿和中部的九龙矿山西组2号煤为研究对象,分析煤中微量元素地球化学特征,探讨锂元素及稀土元素赋存状态和同一煤层不同矿井间煤中微量元素的差异性及其控制因素。
峰峰矿区位于太行山山前断裂带影响范围内,属华北构造赋煤区的太行山东麓断阶赋煤构造带[19-20],是邯邢煤田的重要组成部分,矿区内断裂构造较为发育,以北北东—北东向正断层为主,主要褶皱鼓山背斜和和武安—和村向斜位于西部,纵贯南北(图1)。鼓山背斜将矿区分为东西两部分,西侧为武安—和村向斜;东侧为向SEE缓倾的单斜[20]。矿区主要含煤地层为晚古生代石炭—二叠系太原组和山西组,含可采及局部可采煤层7层,2号煤及9号煤为全区稳定可采煤层,其中2号煤发育在山西组中部,顶板为粉砂岩,底板为炭质泥岩,南部厚度大而稳定,向北有分叉变薄的趋势。
峰峰矿区山西组地层岩性以砂岩、粉砂岩及泥岩为主,成煤环境主要为三角洲平原[21],沉积主要受控于自北向南的河流作用。燕山期岩浆分布于矿区北部武安一带,主要侵入地层为奥陶系及石炭—二叠系,导致煤变质程度呈现出北高南低的变化规律,矿区煤类的分布属于典型的中深成区域岩浆热变质作用的结果[22],岩浆热液是峰峰矿区的煤变质 的主导因素之一[18]。
图1 峰峰矿区构造简图(左)和2号煤层垂向采样剖面(右)
Fig.1 Tectonic sketch of Fengfeng mining area (left) and the vertical sampling section of No.2 coal (right)
样品采自峰峰矿区南部的梧桐庄矿和中部的九龙矿2号煤层的采煤工作面,自上而下分层刻槽采样。梧桐庄矿采样16件,包括煤样14件,顶底板各1件;九龙矿采样16件,包括煤样15件,顶板样1件(图1)。所有采集的样品被立即储存在密封袋中,以避免污染和氧化。
显微组分鉴定依据国家标准GB/T 15588—2013《烟煤显微组分分类》和GB/T 8899—2013《煤的显微组分组和矿物测定方法》,在油浸反射偏光显微镜下,按固定步长统计不少于500个点,以各显微组分和矿物的统计点数占总有效点数的百分数(视为体积分数)为最终鉴定结果。基于国家标准GB/T 212—2008《煤的工业分析方法》进行煤的工业分析,煤中全硫和各种形态硫的测定参照GB/T 214—2007《煤中全硫的测定方法》和GB/T 215—2003《煤中各种形态硫的测定方法》。使用原子吸收光谱仪(AAS)及X射线荧光光谱仪(XRF)分析煤灰中常量元素氧化物,包括K2O,Na2O,SiO2,Al2O3,Fe2O3,CaO,MgO,TiO2,电感耦合等离子体质谱仪(ICP-MS)测定样品中的微量元素,带能谱的扫描电镜(SEM-EDS)对煤中矿物种类及元素组成进行鉴定。上述实验测试均在中国煤炭地质总局煤系矿产资源重点实验室完成。
梧桐庄矿2号煤样的镜质体平均随机反射率(Rran)为0.99%,其显微煤岩组分以镜质组为主,其含量为46.2%~74.3%,平均值为59.9%;惰质组次之,其含量为17.4%~45.1%,平均值为31.2%;壳质组含量最少,其含量为0.5%~3.2%,平均值为2.1%;无机矿物含量为4.0%~11.3%,平均值为6.8%(表1)。而矿区中部的九龙矿2号煤样的镜质体平均随机反射率为1.25%,其显微煤岩组分以镜质组为主,其含量为46.4%~70.5%,平均值为57.9%;惰质组次之,其含量为14.0%~48.9%,平均值为33.5%;无机矿物含量为2.6%~28.5%,平均值为8.6%(表1)。两煤矿2号煤的镜质体平均随机反射率不同,九龙矿2号煤的变质程度高于梧桐庄矿。两煤矿2号煤的镜质组分含量特征相似,主要由基质镜质体及均值镜质体组成,结构镜质体含量较小,偶见碎屑镜质体。在显微镜下常见基质镜质体被黏土矿物所浸染(图2(a),(d));惰质组分主要由半丝质体和碎屑惰质体组成,氧化丝质体也占有一定比例。梧桐庄矿煤样中的壳质组分含量较少,小孢子体为煤样壳质组的主要组成部分,偶见树皮体及树脂体。而九龙矿煤样中在显微镜下未见到壳质组分。
显微镜下鉴定结果,九龙矿煤样的无机矿物含量比梧桐庄矿的略高。梧桐庄矿2号煤中无机矿物主要由黏土类矿物及碳酸岩类矿物组成,而九龙矿2号煤中无机矿物主要由黏土类矿物组成。梧桐庄2号煤显微镜下可见充填状的方解石及黄铁矿(图2(b),(c)),扫描电镜下可见白云石及菱铁矿(图3(a),(b))。九龙矿2号煤样品可见热液成因的黄铁矿(图2(e)),少见方解石,偶见石英颗粒(图2(f)),扫描电镜下可见被白云化的铁白云石,亦可见高岭石及伊利石(图3(f)),偶见磷灰石(图3(d))及充填状方解石(图3(e))。
表1 梧桐庄矿2号煤(WTZ)和九龙矿2号煤(JL)样品煤岩组分含量
Table 1 Macerals contents of No.2 coal samples from Wutongzhuang coal mine and Jiulong coal mine %
样品编号TC1C2C3VDVFSfMaMiIDISpCuReBaECMSMCaMSiMMWTZ-012.414.853.801.071.92.912.401.45.722.41.00001.04.300.504.8WTZ-024.213.441.700.559.76.015.70.50.58.331.01.40001.45.102.807.9WTZ-034.110.157.30.50.572.55.58.70.50.94.119.70.50.500.93.20.53.206.9WTZ-042.83.751.40057.91.416.200.510.628.70.51.40.902.85.10.54.60.510.6WTZ-052.313.144.60.51.962.42.810.80.51.47.523.01.41.40.503.38.50.91.9011.3WTZ-060.512.451.500.564.94.515.80.53.04.528.20.51.0001.53.50.51.505.4WTZ-071.36.541.70.90.450.93.520.902.612.239.12.21.30.403.95.70.4006.1WTZ-083.09.135.90.51.550.03.524.70.53.010.642.41.02.0003.04.000.504.5WTZ-090.920.750.20.5072.45.110.600.93.720.30.90000.91.41.43.706.5WTZ-100.526.346.900.574.20.912.20.50.93.317.80.91.400.52.83.801.405.2WTZ-110.515.530.60046.61.425.70.50.516.544.601.90.50.52.94.401.505.8WTZ-120.917.027.40.40.446.24.921.51.81.813.543.50.42.700.94.04.002.206.3WTZ-131.014.835.200.551.43.819.02.42.99.537.601.00.501.48.11.00.509.5WTZ-148.511.436.31.00.557.74.020.41.51.510.437.80.50000.53.5000.54.0均值2.413.543.20.30.659.93.616.80.71.68.631.20.81.00.20.12.24.60.41.70.16.8JL-0122.014.530.00.53.570.54.55.5004.014.00000012.01.002.515.5JL-0210.12.932.71.90.548.13.819.22.40.517.343.300.50.5006.301.40.58.2JL-0310.69.249.80069.65.310.61.02.95.325.1000004.300.50.55.3JL-047.99.836.00053.73.322.901.411.739.30.500.5006.50006.5JL-055.88.747.600.562.57.212.502.97.730.3000007.20007.2JL-069.411.227.200.948.75.811.6005.422.80000028.100.4028.6JL-077.813.238.01.00.560.55.915.60.50.59.331.7000007.80007.8JL-0814.419.830.71.50.566.84.512.41.0010.928.7000004.0000.54.5JL-0910.512.332.90055.73.726.000.59.639.7000003.200.90.54.6JL-103.89.146.400.559.88.614.801.07.231.6000006.202.408.6JL-115.96.852.30.9065.82.718.00.90.97.229.7000004.100.504.5JL-124.64.635.801.446.36.023.40.50.59.639.90000012.40.50.9013.8JL-132.26.138.90.40.948.57.022.31.70.417.548.9000002.60002.6JL-145.81.439.41.4048.16.727.41.00.510.145.7000004.801.406.3JL-155.710.046.21.00.563.33.319.01.01.47.131.9000003.301.404.8均值8.49.338.90.60.657.95.217.40.70.99.333.5000.1007.50.10.70.38.6
注:T为结构镜质体;C1为均质镜质体;C2为基质镜质体;C3为团块镜质体;VD为碎屑镜质体;V为镜质组;F为丝质体;Sf为半丝质体;Ma为粗粒体;Mi为微粒体;ID为碎屑惰质体;I为惰质组;Sp为孢子体;Cu为角质体;Re为树脂体;Ba为树皮体;E为壳质组;CM为黏土类;SM为硫化物类;CaM为碳酸盐类;SiM为氧化硅类;M为矿物质。
矿区南部的梧桐庄矿2号煤为肥煤,原煤灰分产率(Ad)加权平均值为11.5%,全硫(St.d)含量加权平均值为0.53%(表2),属低灰低硫煤(据GB15224.1—2018和GB15224.2—2010),形态硫测试结果表明,以有机硫为主。矿区中部的九龙矿2号煤为焦煤,原煤灰分产率为14.9%(表3),略高于梧桐庄矿,而全硫含量为0.37%,略低于梧桐庄矿,属低灰特低硫煤。矿区由于受到后期构造热演化及岩浆的影响,煤层的变质程度略有差异,煤体结构破坏严重,原生结构不清晰,硬度较低。
表4列出了梧桐庄矿和九龙矿2号煤中常量元素氧化物含量。梧桐庄矿2号煤中常量元素氧化物以SiO2,Al2O3和CaO为主,SiO2 含量为2.93%~6.90%,均值为4.32%;Al2O3含量为2.53%~5.57%,均值为3.63%;CaO含量为0.37%~2.61%,均值为1.17%;SiO2/Al2O3含量比为1.19。九龙矿2号煤中常量元素氧化物以SiO2和Al2O3为主,SiO2含量为3.83%~13.82%,均值为6.81%,Al2O3含量为3.26%~11.48%,均值为5.62%;SiO2/Al2O3含量比为1.21。梧桐庄矿2号煤中常量元素氧化物SiO2和Al2O3含量低于九龙矿。
图2 油浸反射光显微镜下显微煤岩组分((a)~(c)梧桐庄矿,(d)~(f)九龙矿)
Fig.2 Macerals under the oil immersion and reflected light microscopy
图3 扫描电镜下矿物照片((a)~(c)梧桐庄矿,(d)~(f)九龙矿)
Fig.3 Minerals images under SEM (a,b,c from Wutongzhuang coal mine,and d,e,f from Jiulong coal mine)
表2 梧桐庄矿2号煤样品工业分析数据
Table 2 Proximate analysis of No.2 coal samples from Wutongzhuang coal mine %
参数WTZ-01WTZ-02WTZ-03WTZ-04WTZ-05WTZ-06WTZ-07WTZ-08WTZ-09WTZ-10WTZ-11WTZ-12WTZ-13WTZ-14均值Mad0.60.70.60.60.70.80.70.60.60.70.60.90.50.50.65Ad15.615.112.713.39.89.28.07.910.511.913.412.19.911.111.5Vdaf32.333.535.431.032.232.429.128.934.032.227.729.830.131.431.4St.d0.60.50.60.40.60.60.50.50.70.50.40.40.50.60.53Sp.d0.10.10.10.10.20.20.10.10.100.100.20.10.11So.d0.50.40.50.30.40.30.30.30.30.30.30.30.30.40.35
表3 九龙矿2号煤样品工业分析数据
Table 3 Proximate analysis of No.2 coal samples from Jiulong coal mine %
样品编号JL-01JL-02JL-03JL-04JL-05JL-06JL-07JL-08JL-09JL-10JL-11JL-12JL-13JL-14JL-15均值Mad0.80.60.60.50.90.50.60.30.40.50.50.70.40.50.50.6Ad20.918.818.414.18.928.412.612.214.515.712.913.710.511.010.714.9Vdaf27.721.624.924.724.327.324.024.524.024.624.424.523.323.825.024.6St.d0.60.30.40.40.40.30.40.40.30.30.40.40.30.40.40.4Sp.d0.300.100.100.100000.10000.1So.d0.30.30.30.30.40.20.30.40.30.30.30.30.30.30.40.3
表4 2号煤中常量元素氧化物含量
Table 4 Content of major element oxides of No.2 coal samples
样品编号K2ONa2OSiO2Al2O3Fe2O3CaOMgOTiO2SiO2/Al2O3WTZ-010.110.146.905.570.560.620.320.221.24WTZ-020.060.045.454.510.292.021.210.151.21WTZ-030.040.083.943.350.442.610.890.091.18WTZ-040.070.095.114.230.491.570.340.171.21WTZ-050.010.103.482.930.641.070.330.161.19WTZ-060.010.133.352.830.610.820.330.151.18WTZ-070.010.163.212.700.500.390.220.151.19WTZ-080.010.173.162.710.440.410.200.131.17WTZ-090.010.122.932.531.051.710.810.081.16WTZ-100.020.144.073.530.861.470.600.131.15WTZ-110.030.135.814.950.420.780.180.221.18WTZ-120.020.154.894.180.451.130.200.171.17WTZ-130.020.133.613.090.591.140.230.081.17WTZ-140.070.084.553.680.600.700.370.151.24JL-010.130.0610.466.950.890.410.240.341.51JL-020.070.089.397.670.180.160.060.251.22JL-030.050.068.356.770.900.450.150.431.23JL-040.060.016.805.680.200.200.070.281.20JL-050.070.043.833.260.340.370.050.121.17JL-060.090.1313.7211.480.630.350.200.241.20JL-070.050.145.955.020.410.160.060.231.19JL-080.050.155.944.900.300.180.060.251.21JL-090.040.206.555.600.520.500.060.291.17JL-100.050.186.866.050.620.670.080.261.14JL-110.030.195.554.890.500.620.050.191.13JL-120.050.185.724.630.700.890.100.171.24JL-130.010.254.233.660.290.910.090.081.16JL-140.010.254.313.750.371.100.080.091.15JL-150.020.174.563.950.320.750.070.111.16WTZ-均值0.040.124.323.630.571.170.450.151.19JL-均值0.050.146.815.620.480.510.090.221.21
电感耦合等离子体质谱法(ICP-MS)测定煤及顶底板样品中微量元素结果见表5。梧桐庄矿2号煤中Li元素含量为36.1~74.6 μg/g,平均49.8 μg/g。九龙矿2号煤中Li含量为30.5~172.7 μg/g,平均64.3 μg/g,煤层中部JL-06煤样的Li元素含量最高,为172.7μg/g。与世界煤中微量元素相比[23],梧桐庄矿2号煤中只有Li元素表现轻微富集(图4(a)),九龙矿2号煤中Li元素表现富集,Y,Nb,Pb,La,Er,Ta,Th表现为轻微富集(图4(b))。由图5可看出,梧桐庄矿2号煤中各微量元素相对含量特征与九龙矿类似,但含量存在差异,除Ge外,九龙矿2号煤中其他微量元素含量均大于梧桐庄矿。梧桐庄矿2号煤顶板中Li元素含量为25.9 μg/g,底板中Li元素含量为116 μg/g。九龙矿2号煤顶板中Li元素含量为156.8 μg/g。与世界黏土中Li元素的均值54 μg/g相比[24],梧桐庄矿2号煤顶板中Li元素含量略低,而九龙矿2号煤顶板中Li元素含量略高,但两矿2号煤顶板中Li元素均未达到富集。总之,九龙矿2号煤及顶板中Li元素含量均高于梧桐庄矿。虽然九龙矿2号煤中Li元素表现富集,特别是JL-06样品分层出现异常高值,但其Li元素含量均值64.3 μg/g低于管板乌素、哈尔乌素和平朔矿区山西组煤层中Li元素含量[13-14,25-26],也不满足孙玉壮等提出的原煤中锂的回收利用指数(120 μg/g)[27]。从现今的技术经济角度来看,两矿的Li元素还不具备经济资源价值。
表5 2号煤中微量元素含量
Table 5 Trace element contents of No.2 coal samples
μg/g
样品编号LiBeScCrCoNiCuZnGaGeVRbSrYNbMoCdInCsPbWTZ-顶25.91.57.335.48.214.717.572.016.81.132.156.6166.020.512.80.90.10.12.319.1WTZ-0138.10.73.07.42.14.629.83.64.50.557.43.181.99.84.00.9000.311.2WTZ-0245.18.211.915.87.213.621.17.112.219.22.41.9243.020.36.80.8000.216.1WTZ-0344.21.52.57.15.78.617.210.06.50.69.11.2208.114.22.41.5000.19.7WTZ-0454.81.04.911.62.86.339.25.65.30.435.23.0155.215.35.61.3000.314.4WTZ-0551.70.83.810.02.26.116.37.04.40.616.10.4154.914.33.71.7000.18.0WTZ-0643.30.62.57.81.48.111.44.44.30.53.20.5167.610.75.61.3000.18.2WTZ-0745.00.62.310.71.26.59.08.72.40.34.60.5155.78.73.41.0000.14.8WTZ-0851.80.62.410.61.16.39.65.22.40.42.10.5159.28.93.21.0000.15.0WTZ-0936.10.41.84.71.611.35.99.37.60.33.10.5238.77.32.51.6000.18.1WTZ-1052.10.73.67.81.98.819.34.76.20.32.51.5201.510.55.21.4000.212.9WTZ-1174.60.83.98.61.06.918.65.64.80.34.20.9178.09.07.10.7000.112.5WTZ-1267.70.73.69.21.38.421.95.75.20.23.30.7190.78.06.10.8000.117.2WTZ-1343.30.61.55.02.713.08.55.13.80.31.20.8167.86.71.61.1000.16.2WTZ-1449.80.83.99.04.310.131.65.95.40.538.22.9140.112.44.11.4000.215.2WTZ-底116.02.515.952.54.316.319.048.633.61.982.769.0116.020.628.90.800.15.324.4JL-顶156.83.220.350.213.620.2145.8129.137.72.311951.6138.472.024.21.40.60.15.860.3JL-0162.95.016.024.511.518.859.011.218.62.480.77.2101.369.212.32.900.10.922.6JL-0272.85.18.216.91.88.115.86.97.20.34.02.5115.439.26.70.600.10.218.3JL-0364.23.67.016.54.511.027.28.58.00.317.12.0129.934.811.81.400.10.225.4JL-0456.03.45.911.34.711.019.76.67.70.39.02.1109.828.08.01.4000.117.5JL-0530.51.53.15.86.411.610.04.27.10.54.02.5135.116.43.21.9000.19.4JL-06172.71.14.913.03.09.114.916.916.90.87.63.999.214.913.41.6000.327.6JL-0761.91.25.910.03.09.614.16.110.00.510.12.285.813.49.11.5000.116.1JL-0858.11.25.610.92.89.715.722.310.90.62.02.386.613.310.91.5000.216.2JL-0959.60.94.18.71.77.710.35.47.40.21.01.5549.214.68.30.8000.114.5JL-1068.51.04.58.82.17.514.45.87.90.210.01.7482.017.86.70.9000.214.7JL-1150.50.83.56.11.77.111.04.55.80.25.51.1511.013.45.60.9000.113.9JL-1252.20.93.69.52.69.312.97.87.30.41.01.8329.213.56.11.3000.211.8JL-1351.10.82.99.81.68.615.44.23.70.13.30.5124.69.22.11.0000.15.7JL-1451.30.72.78.62.09.514.15.95.00.22.40.5127.98.72.61.4000.16.8JL-1552.60.83.36.62.410.411.45.47.20.33.20.6103.58.16.81.6000.111.6WTZ-均值49.81.33.78.92.68.518.56.35.41.713.01.3174.511.24.41.2000.210.7JL-均值64.31.95.411.13.49.917.78.18.70.510.72.2206.021.07.61.4000.215.5世界煤均值12.01.63.916.05.113.016.023.05.82.428.07.8110.08.43.72.20.20.01.37.8世界黏土均值54.03.015.0110.019.049.036.089.016.0120.0133.0240.031.01.60.90.113.014.0
续 表
样品编号BiBaLaCePrNdSmEuGdTbDyHoErTmYbLuTaTlThUWTZ-顶0.1842.047.487.210.339.56.51.35.50.84.10.82.10.31.90.310.410.21.7WTZ-010.297.314.627.53.212.42.20.41.90.31.80.41.00.11.00.10.40.151.8WTZ-020.2117.07.314.71.97.81.70.41.70.42.90.72.10.32.30.40.40.14.11.2WTZ-030.1101.37.315.02.19.02.00.41.90.32.40.51.40.21.30.20.20.12.51.1WTZ-040.2103.714.127.53.313.62.70.52.30.42.60.61.60.21.50.20.40.26.02.6WTZ-050.180.015.128.73.413.22.60.52.20.42.40.51.40.21.30.20.30.13.91.1WTZ-060.1103.315.426.12.810.11.80.31.60.31.70.31.00.10.90.10.40.13.81.1WTZ-070.1105.914.625.32.710.11.70.31.50.21.40.30.80.10.80.10.30.13.60.7WTZ-080.1110.815.326.52.810.31.70.31.60.21.50.30.90.10.80.10.30.13.40.7WTZ-090.186.512.621.42.17.81.30.21.30.21.30.30.70.10.60.10.10.12.10.9WTZ-100.2105.514.126.02.710.51.90.31.70.32.00.41.10.21.00.10.40.16.02.1WTZ-110.2115.714.225.42.69.21.60.31.50.21.60.30.90.10.80.10.70.18.82.2WTZ-120.3108.414.624.62.48.81.50.31.40.21.50.30.80.10.80.10.50.16.32.4WTZ-130.182.711.719.82.07.41.30.21.20.21.20.20.70.10.60.10.10.12.10.6WTZ-140.2130.59.417.82.18.61.80.41.70.32.00.41.20.21.20.20.30.14.42.1WTZ-底0.3203.025.648.85.922.04.21.13.50.63.70.82.20.42.30.41.90.418.33.4JL-顶0.7448.2155.4293.840.8155.830.45.423.23.317.13.18.41.27.61.12.10.731.313.1JL-010.4174.884.6157.217.669.512.72.211.41.711.52.46.50.95.90.80.70.317.34.9JL-020.3114.033.870.37.830.65.61.05.00.85.81.33.60.53.50.50.80.116.32.2JL-030.3134.631.364.27.328.45.40.94.70.85.21.13.20.53.10.41.00.115.42.7JL-040.3128.619.038.34.517.03.30.63.00.53.90.92.50.42.60.40.60.110.01.9JL-050.1199.315.329.43.312.72.50.42.10.42.40.51.50.21.40.20.20.12.40.7JL-060.2247.324.546.54.918.03.30.62.80.42.70.51.50.21.50.21.20.214.13.0JL-070.2206.86.814.61.87.01.60.31.40.32.10.51.40.21.50.20.50.16.82.5JL-080.3201.96.815.11.87.01.50.31.40.32.00.51.30.21.50.20.60.17.72.4JL-090.3340.235.156.25.619.43.10.52.90.42.60.51.40.21.20.20.80.212.52.6JL-100.2349.822.544.85.420.83.40.63.00.53.00.61.70.21.60.20.50.28.82.2JL-110.2289.237.860.55.719.83.30.63.00.42.50.51.30.21.10.20.60.210.61.9JL-120.2242.622.440.64.215.22.70.52.40.42.30.51.30.21.20.20.50.27.01.6JL-130.2152.63.514.12.18.92.00.31.50.21.60.30.90.10.90.10.20.22.90.7JL-140.2127.53.412.61.87.61.70.31.30.21.50.30.90.10.90.10.20.23.10.8JL-150.2114.71.74.20.62.80.80.20.70.21.20.30.80.10.90.10.40.16.31.5WTZ-均值0.2103.512.923.32.69.91.90.41.70.31.90.41.10.21.10.20.30.14.41.5JL-均值0.2201.623.244.65.019.03.50.63.10.53.40.72.00.31.90.30.60.29.42.1世界煤均值1.0150.011.023.03.512.02.00.52.70.32.10.50.90.31.00.20.30.63.32.4世界黏土均值0.38460.048.075.010.036.08.01.25.80.834.40.91.90.52.50.391.41.314.04.3
图4 梧桐庄矿和九龙矿2号煤微量元素富集系数
Fig.4 Concentration coefficient of trace elements in 2 coal of Wutongzhuang coal mine and Jiulong coal mine
图5 九龙矿2号煤、梧桐庄矿2号煤与世界煤(Ketris,2009)微量元素浓度均值
Fig.5 Average concentrations of trace elements in coal from Wutongzhuang coal mine,Jiulong coal mine,and the world coal
梧桐庄矿2号煤中REY含量在53.6~86.768 μg/g,平均为68.8 μg/g,与世界煤中REY均值(68 μg/g)相当。九龙矿2号煤中REY含量在22.6~453.9 μg/g,平均为130 μg/g,高于世界煤中REY均值近两倍,最高值出现在靠近煤层顶板的JL-01,为世界煤的6.7倍。梧桐庄矿2号煤中REY含量远低于九龙矿煤中REY含量(表6)。梧桐庄矿2号煤顶板和底板中REY含量分别为228.5 μg/g和142.0 μg/g,其顶板中REY含量与世界黏土中平均REY含量(226.42 μg/g)[24]相当,比大陆上地壳中REY含量(168.37 μg)[28] 略高。其底板中REY含量低于世界黏土中和大陆上地壳中REY含量。九龙矿2号煤顶板中REY含量为818.6 μg/g,分别高于世界黏土中和大陆上地壳平均REY含量的3.6倍和4.9倍。梧桐庄矿2号煤顶板中REY含量远低于九龙矿顶板中REY含量。整体上,九龙矿2号煤及顶板中REY含量均高于梧桐庄矿2号煤及顶板中REY含量。华北地区煤的大部分样品稀土元素含量平均56 μg/g,煤的顶底板中平均167 μg/g[9]。梧桐庄矿2号煤及顶板中REY含量与华北地区平均值相当,而九龙矿2号煤及顶板中REY含量高于华北地区平均值。但与煤层中稀土元素富集的内蒙古大青山、黑岱沟、哈尔乌素和阿刀亥矿等[25-26]相比,九龙矿煤中稀土元素含量较低,未达到工业品位。迄今为止我国鲜有发现真正意义上的煤型稀土矿床[9]。
本文研究采用将REY分为轻稀土元素(LREY:La,Ce,Pr,Nd,Sm),中稀土元素(MREY:Eu,Gd,Tb,Dy,Y)和重稀土元素(HREY:Ho,Er,Tm,Yb,Lu)的三分法[29],选用上地壳(UCC)数据[24]作为标准对稀土元素数据进行标准化,用标准化的La,Sm,Gd和Lu的比值(L型,LaN/LuN>1;M 型,LaN/SmN<1且GdN/LuN>1;H型,LaN/LuN<1)对轻、中、重稀土元素的富集类型进行判断[29-30]。稀土元素的标准化分布模式可以综合的、直观的反映稀土元素的地球化学特征[31]。图6为采用了上地壳(UCC)数据标准化后的稀土元素标准化曲线,两个矿2号煤的稀土元素分布曲线相似。梧桐庄矿2号煤中LaN/LuN在0.21~1.45,平均为1.03,以轻稀土富集型为主,稀土元素分馏不明显;九龙矿2号煤中LaN/LuN在0.14~2.39,平均为0.88(表6),稀土元素富集类型具有多样性,以重稀土富集型为主,稀土元素存在分馏,样品JL-01至JL-04与其他样品分馏明显。
通常沉积源区为酸性岩会造成Eu及Ce的负异常,火山热液或海水的影响则会导致Y或Ce的正异常[29]。梧桐庄矿2号煤样的δEu在0.88~0.95,平均为 0.92,δCe在0.84~1.16,平均0.93,δY在0.95~1.08,平均1.04。九龙矿2号煤样的δEu在 0.90~1.09,平均为0.96,δCe在0.83~1.03,平均0.90,δY在0.99~1.06,平均1.07(表6)。两个矿2号煤均具有微弱的Eu负异常、Ce负异常和Y正异常,反映了沉积源区均为酸性岩,且可能受到热液影响。梧桐庄矿煤层及底顶板具有微弱的Ce和Eu负异常,Y正异常不明显,煤层与顶底板稀土元素分布曲线相似,表明梧桐庄矿煤层及其顶底板具有相似且稳定的物源,且受到岩浆热液的影响不明显。而在九龙矿煤层上部(JL-02~JL-04)中Y具有明显的正异常特征,表明九龙矿煤层上部可能受岩浆热液的影响。
表6 稀土元素地球化学参数
Table 6 REY geochemical parameters
样品编号REYLREYMREYHREY(La/Lu)N(La/Sm)N(Gd/Lu)NδEuδCeδYWTZ-顶228.46190.932.25.41.631.091.480.901.060.96 WTZ-0176.6459.914.12.61.071.001.080.920.910.99WTZ-0264.9633.425.85.80.210.630.400.901.161.08WTZ-0358.0735.319.23.60.400.540.800.881.031.06WTZ-0486.3761.121.24.10.690.780.890.920.981.01WTZ-0586.3863.019.83.60.870.881.000.920.951.03WTZ-0673.2156.214.62.41.321.291.110.900.901.14WTZ-0768.7554.412.22.21.311.271.080.920.901.10WTZ-0871.3956.612.52.31.351.331.080.920.891.07WTZ-0957.4145.210.41.81.471.411.150.920.871.02WTZ-1072.9955.314.92.81.021.100.990.950.900.95WTZ-1167.9853.112.62.31.261.301.030.950.841.00WTZ-1265.4651.911.42.11.431.421.070.930.880.97WTZ-1353.5642.39.51.71.451.341.170.920.861.01WTZ-1459.4539.616.83.10.580.770.810.910.961.08WTZ-底141.98106.529.56.00.760.920.830.901.290.95WTZ-均值68.7650.5215.362.891.031.080.980.920.931.04JL-顶818.57676.1121.021.41.530.771.810.840.960.84JL-01453.93341.696.016.41.091.001.150.930.861.07JL-02209.11148.051.89.30.690.910.810.990.871.13JL-03191.24136.646.48.30.750.870.880.970.851.15JL-04125.0382.336.06.70.550.860.680.940.891.15JL-0588.8063.221.83.80.810.930.900.940.881.16JL-06122.5397.321.34.01.191.131.050.970.890.99JL-0753.1131.817.53.80.330.630.550.960.941.04JL-0853.2432.217.33.80.310.660.510.990.941.07JL-09143.91119.421.03.52.011.701.310.900.831.07JL-10126.3397.025.04.41.060.981.110.930.871.05JL-11150.28127.119.93.32.391.741.480.920.861.00JL-12107.3985.019.13.31.361.231.150.950.901.05JL-1345.8730.512.92.40.280.270.911.070.961.02JL-1441.3127.012.02.30.290.310.851.090.961.02JL-1522.6210.210.22.20.140.310.430.901.031.12JL-均值128.9895.2828.555.170.880.900.920.960.901.07
注:REY,LREY,MREY和 HREY的单位为 μg/g;(La/Yb)N,(La/Sm)N,(Gd/Yb)N为标准化后比值;δEu=EuN/(0.5SmN+0.5GdN);δCe=CeN/(0.5LaN+0.5PrN);δY=YN/HoN。
图6 样品稀土元素分布模式
Fig.6 REY distribution patterns of sample
据报道,不同地区煤中锂元素的赋存状态不同,锂元素主要赋存于煤中无机组分或有机组分中。锂元素往往与无机组分有较强的正相关性关系,硅铝酸盐、高岭石、绿泥石等黏土矿物是锂的主要载体[13-14,32-34]。Lewinska-Preis等发现在挪威Longyearbyen矿的煤中72%的Li与有机质结合[35]。梧桐庄矿与九龙矿2号煤中Li元素分别为轻度富集和富集状态。
梧桐庄矿2号煤中Li元素含量与灰分产率之间相关性不明显(图7),表明Li元素与无机组分相关性不明显,Li元素可能赋存于有机质中。通过梧桐庄矿煤中Li元素含量与煤中显微组分相关关系分析(表7),煤中Li元素含量与有机显微组分具有显著相关性,与碎屑惰质体(ID)、角质体(Cu)、树皮体(Ba)和半丝质体(Sf)呈显著正相关关系,相关系数均在0.6以上。通过Li元素与煤中常量元素氧化物相关关系分析(表8),梧桐庄矿煤中Li元素含量与常量元素氧化物相关性不明显。这些均证明梧桐庄矿2号煤中Li元素可能赋存于煤的有机质中。
图7 煤中Li,REY含量与灰分产率相关关系
Fig.7 Correlation between ash yield and Li or REY
表7 Li,REY元素含量分别与煤中显微组分Pearson相关系数
Table 7 Pearson correlation coefcients between Li or REY and maceral contents
项目TC1C2C3VDFSfMaMiIDSp2CuReBaCMSMCaMSiM梧桐庄矿Li-0.153 0.027 -0.670 -0.102 -0.141 -0.419 0.61010.233 -0.226 0.7482-0.381 0.75720.235 0.75620.090 -0.467 0.031 0.099 九龙矿Li0.165 0.144 -0.493 -0.151 0.109 0.040 -0.284 -0.166 -0.372 -0.231 -0.073 0.074 000.8512-0.061 0.026 -0.017 梧桐庄矿REY0.75820.154 -0.247 -0.121 0.6972-0.233 -0.523 -0.174 -0.111 -0.332 -0.010 0.210 -0.190 -0.063 0.303 -0.159 0.158 0.175 九龙矿REY-0.163 -0.257 0.258 -0.248 0.404 -0.590 -0.116 -0.518 -0.133 0.018 0.298 0.339 000.226 0.7582-0.122 0.190
注:1表示在0.05级别(双尾),相关性显著;2表示在0.01级别(双尾),相关性显著,表8同。
表8 煤样中Li,REY分别与煤中常量元素氧化物Pearson相关系数
Table 8 Pearson correlation coefcient between Li or REY and major element oxides of coal samples
项目K2ONa2OSiO2Al2O3Fe2O3CaOMgOTiO2梧桐庄矿Li-0.150 0.1600.3000.350-0.380 -0.180-0.4200.510九龙矿Li0.5591-0.0500.84020.90820.240-0.2400.3900.250梧桐庄矿REY0.1500.0800.2100.200-0.090-0.250-0.3000.030九龙矿REY0.7852-0.4800.59410.4400.5851-0.2700.67620.6331
九龙矿煤中Li元素含量与灰分产率之间具有较好的正相关关系(图7),通过九龙矿煤中Li元素含量与煤中显微组分相关关系分析(表7),煤中Li元素含量与黏土类矿物呈显著正相关关系,相关系数为0.851,而与煤中有机显微组分相关性不明显。通过Li元素含量与煤中常量元素氧化物相关关系分析(表8),Li元素含量与常量元素氧化物SiO2和Al2O3呈显著正相关关系,相关系数在0.8以上,与K2O相关性明显,相关系数为0.559,但与MgO,Fe2O3相关性较差,表明九龙矿2号煤Li元素与黏土矿物有较强的亲和性,Li元素主要赋存于黏土矿物中。同时,在SEM-EDS下发现九龙矿样品中含有较多的高岭石及伊利石矿物(图3(d)~(f)),这些均表明Li元素赋存于高岭石和伊利石等黏土矿物中。
通常,煤中稀土元素和钇(REY)以无机结合态为主,其含量与灰分产率具有很高的正相关关系,常见的含REY的矿物有氟碳铈矿、独居石、磷钇矿或者被黏土矿物吸附[9]。任德贻等对低灰分煤中REE研究表明,各REE含量虽较低,但大多数REE与有机质结合的比例超过50%[5,36],王文峰等运用有机溶剂萃取的方法同样发现煤的有机组分中REE的存在[37]。刘贝和黄文辉等研究发现沁水盆地晚古生代煤稀土元素主要赋存于黏土矿物中,黄铁矿脉中富集稀土元素,碳酸盐矿物和氧化物中稀土元素含量较低,相当部分的稀土元素赋存于有机质中[31]。
通过REY元素含量与灰分产率相关分析(图7),梧桐庄矿2号煤样品中REY含量与灰分产率之间无明显相关性。通过煤中REY元素含量与煤中显微组分相关关系分析(表7),煤中REY含量与有机显微组分具有相关性,与结构镜质体(T)和碎屑结构镜质体(VD)呈显著正相关关系,相关系数分别为0.758和0.697。通过REY元素与煤中常量元素氧化物相关关系分析(表8),梧桐庄矿煤中REY元素含量与常量元素氧化物相关性不明显。因此,梧桐庄矿2号煤中REY元素可能赋存于煤的有机质中。
通过REY元素含量与灰分产率相关分析(图7),九龙矿2号煤中REY含量与灰分产率之间呈正相关关系,表明九龙矿2号煤中REE主要赋存于无机矿物中。通过煤中REY元素含量与煤中显微组分相关关系分析(表7),煤中REY含量与无机矿物具有显著相关性,与硫化物类无机矿物呈正相关关系。通过REY元素与煤中常量元素氧化物相关关系分析(表8),REY与常量元素氧化物中的SiO2,Fe2O3,K2O,MgO,TiO2具有较好的正相关性。SEM-EDS图像和能谱结果显示,稀土元素的载体矿物独居石,主要含La,Ce,Nd等轻稀土元素以及放射性元素Th(图8)。因此,九龙矿2号煤中REY赋存于无机矿物中,主要赋存于独居石、黄铁矿和黏土矿物中。
矿区中部的九龙矿及矿区南部的梧桐庄矿2号煤中微量元素地球化学特征及赋存既有相似性,又存在差异。九龙矿2号煤中微量元素含量整体比梧桐庄矿高,九龙矿2号煤中REY及Li主要赋存于无机矿物中,而梧桐庄矿2号煤中REY及Li主要赋存于有机组分中。
图8 SEM-EDX下九龙矿煤样中矿物及能谱
Fig.8 Mineral and energy spectrum image in coal samples from jiulong mine under SEM-EDX
古生代至中生代华北克拉通盆地与中亚造山带相关的俯冲增生和碰撞形成北侧的阴山-燕山造山带,使其长期处于隆升剥蚀状态,持续为整个华北盆地提供物源[19]。代世峰、孙玉壮等[13,25-26]对准格尔煤田和平朔矿区煤中Li研究认为北部阴山古陆的钾长花岗岩为Li的主要来源。峰峰矿区位于华北聚煤盆地中东部,结合邵龙义等[17]对华北早二叠世岩相古地理的研究,古水系自北向南流,物源主要来自盆地北部。峰峰矿区山西组为过渡相三角洲沉积环境[17,21],2号煤层主要发育在三角洲平原之上。REY分布模式在两煤矿2号煤具有相似性(图6),反映出沉积物源的一致性。通过稀土元素Eu,Ce,Y的异常分析,两个煤矿2号煤具有微弱的Eu负异常和Ce的负异常,反映了沉积源均为酸性岩。因此,阴山古陆可能是本区煤中Li的主要沉积物源。
镜质组(V)与惰质组(I)的比值能反映出成煤沼泽水位的变化(图9),是研究沼泽环境的重要指标[38]。两煤矿2号煤的沼泽水位变化特征基本相似,前期均出现高—低—高—低的变化,到后期均出现低—高—低—高的变化,反映两煤矿的沼泽水位受同一主要水源的控制。
图9 九龙矿及梧桐庄矿2号煤镜惰比(V/I)变化曲线
Fig.9 V/I curves of No.2 coal in Jiulong coal mine and Wutongzhuang coal mine
峰峰矿区发育多期燕山期岩浆活动,岩体主要分布在矿区北部和中部,主要有永年县西的紫山岩体、武安一带的洪山岩体、磁山乡北侧的磁山岩体、和村以西的和村岩体等。燕山期岩浆活动对峰峰矿区2号煤层产生重要的影响,矿区中部的九龙矿比矿区南部的梧桐庄矿距离岩体近,煤变质程度较高,煤岩煤质及微量元素受岩浆热液的影响较大,矿区中部的九龙矿2号煤样镜下可见热液成因的黄铁矿(图2(e))。而矿区南部的梧桐庄矿受岩体影响较小,煤变质程度低。代世峰等认为峰峰-邯郸矿区岩浆侵入是煤中B,F,Cl,Br,Hg,As,Co,Cu,Ni,Pb,Sr,Mg,Ca,Mn,Zn,U元素的来源,煤中Sb,Sc,V及其余元素可能是煤所固有的[18]。郑刘根等研究表明岩浆热液作用影响稀土元素的含量[39]。峰峰矿区由于沉积环境和沉积物源的相似,岩浆热液作用是影响两矿2煤中微量元素含量差异的主要因素,主要引起煤中Li,Nb,Pb,Ta,Th,Y,La,Sm,Ce,Er,Yb元素富集,其余微量元素变化不大或没有变化。尤其是稀土元素和Li元素受岩浆热液影响含量增加,九龙矿比梧桐庄矿2号煤中Li元素平均含量高14.5 μg/g,稀土元素平均含量高61.2 μg/g。梧桐庄矿2号煤中只有Li元素表现为轻微富集,而九龙矿2号煤中Li元素表现为富集,Nb,Pb,Ta,Th元素和稀土元素中Y,La,Er元素表现为轻微富集。此外岩浆热液亦导致了九龙矿煤层稀土元素分布的不均一性,出现靠近顶板的JL-01~JL-04稀土元素(REY)含量明显升高,且稀土元素分布模式与其他分层样品相比变化较大。通过稀土元素Eu,Ce,Y的异常分析,表明矿区南部的梧桐庄矿煤层及其顶底板具有相似且稳定的物源,且受到岩浆热液的影响不明显;而矿区中部的九龙矿煤层上部(JL-02~JL-04)可能受岩浆热液的影响,岩浆热液是导致峰峰矿区煤层微量元素富集差异的主要因素之一[18]。因此,峰峰矿区2煤的沉积物源和沉积环境控制了其微量元素分布的总体特征,而燕山期岩浆热液作用导致同一煤层(2号煤层)中微量元素在不同位置(梧桐庄矿和九龙矿)的差异。
(1)九龙矿2号煤层样品中微量元素含量整体比梧桐庄矿高。梧桐庄矿和九龙矿2号煤中Li元素平均含量分别为49.8和64.3μg/g,稀土元素(REY)平均含量分别为68.8和130 μg/g。
(2)梧桐庄矿2号煤中Li元素和REY元素主要赋存于煤的有机质中;九龙矿2号煤中Li元素主要赋存于高岭石和伊利石等黏土矿物中,REY元素主要赋存于独居石、黄铁矿和黏土矿物中。
(3)峰峰矿区2煤的沉积物源和沉积环境控制了其微量元素分布的总体特征,而燕山期岩浆热液作用导致2号煤层中微量元素在矿区南部的梧桐庄矿和矿区中部的九龙矿的差异。
[1] 翟明国,吴福元,胡瑞忠,等.战略性关键金属矿产资源:现状与问题[J].中国科学基金,2019(2):106-111.
ZHAI Mingguo,WU Fuyuan,HU Ruizhong,et al.Critical metal mineral resources:current research status and scientific issues[J].Bulletin of National Natural Science Foundation of China,2019(2):106-111.
[2] FINKELMAN R B,Trace and minor elements in coal[A].ENGEL M H,MACKO S.Organic Geochemistry[C].New York:Plenum Press,1993.
[3] COLIN R W.Analysis and significance of mineral matter in coal seams[J].International Journal of Coal Geology,2002,50( S1-4):135-168.
[4] 唐修义,黄文辉,赵继尧.中国煤中的微量元素[M].北京:商务印书馆,2004.
[5] 任德贻,赵峰华,代世峰,等.煤的微量元素地球化学[M].北京:科学出版社,2006.
[6] SUN Yuzhuang,LI Yanheng,ZHAO Cunliang,et al.Concentrations of Lithium in Chinese Coals[J].Energy Exploration & Exploitation,2010,28(2):97-104.
[7] DAI Shifeng,REN Deyi,CHOU C L,et al.Geochemistry of trace elements in Chinese coals:A review of abundances,genetic types,impacts on human health,and industrial utilization[J].International Journal of Coal Geology,2012,94:3-21.
[8] WANG Wenfeng,QIN Yong,LIU X,et al.Distribution,occurrence and enrichment causes of gallium in coals from the Jungar Coalfield,Inner Mongolia.[J].Science China Earth Sciences,2011,54(7):1053-1068.
[9] 黄文辉,久博,李媛.煤中稀土元素分布特征及其开发利用前景[J].煤炭学报,2019,44(1):287-294.
HUANG Wenhui,JIU Bo,LI Yuan.Distribution characteristics of rare earth elements in coal and its prospects on development and exploitation[J].Journal of China Coal Society,2019,44(1):287-294.
[10] DAI Shifeng,FINKELMAN R B.Coal as a promising source of critical elements:Progress and future prospects[J].International Journal of Coal Geology,2018,186:155-164.
[11] 宁树正,邓小利,李聪聪,等.中国煤中金属元素矿产资源研究现状与展望[J].煤炭学报,2017,42(9):2214-2225.
NING Shuzheng,DENG Xiaoli,LI Congcong,et al.Research status and prospect of metal element mineral resources in China[J].Journal of China Coal Society,2017,42(9):2214-2225.
[12] 代世峰,任德贻,李生盛.内蒙古准格尔超大型镓矿床的发现[J].科学通报,2006,51(2):177-185.
DAI Shifeng,REN Deyi,LI Shengsheng.Discovery of superlarge gallium deposits in Inner Mongolia,Jungar[J].Chinese Science Bulletin,2006,51(2):177-185.
[13] SUN Yuzhuang,ZHAO Cunliang,LI Yanheng,et al.Li distribution and mode of occurrences in Li-bearing coal seam # 6 from the Guanbanwusu Mine,Inner Mongolia,northern China[J].Energy Exploration & Exploitation,2012,30(1):109-130.
[14] SUN Yuzhuang,ZHAO Cunliang,LI Yanheng,et al.Further information of the associated Li deposits in the No.6 coal seam at Jungar Coalfield,Inner Mongolia,Northern China[J].Acta Geologica Sinica,2013,87(4):1097-1108.
[15] DAI Shifeng,REN Deyi,CHOU Chenlin,et al.Geochemistry of trace elements in Chinese coals:A review of abundances,genetic types,impacts on human health and industrial utilization[J].International Journal of Coal Geology,2012,94(2):3-21.
[16] ZHAO Cunliang,QIN Shenjun,YANG Yinchao,et al.Concentration of gallium in the Permo-Carboniferous coals of China[J].Energy Exploration & Exploitation,2009,27(5):333-343.
[17] 赵存良.邯邢矿区煤中伴生矿产及微量元素研究[D].邯郸:河北工程大学,2008.
ZHAO Cunliang.Trace elements and associated ore in Handan-Xingtai coalfield[D].Handan:Hebei University of Engineerin,2008.
[18] DAI Shifeng,REN Deyi.Effects of magmatic intrusion on mineralogy and geochemistry of coals from the Fengfeng-Handan Coalfield,Hebei,China[J].Energy & Fuels,2007,21:1663-1673.
[19] 曹代勇,宁树正,郭爱军,等.中国煤田构造格局与构造控煤作用[M].北京:科学出版社,2018.
[20] 曹代勇,占文峰,张军,等.邯郸—峰峰矿区新构造特征及其煤炭资源开发意义[J].煤炭学报,2007,32(2):141-145.
CAO Daiyong,ZHAN Wenfeng,ZHANG Jun,et al.Neotectonic character of Handan - Fengfeng mining area and its significance for coal resource exploitation[J].Journal of China Coal Society,2007,32(2):141-145.
[21] 邵龙义,董大啸,李明培,等.华北石炭—二叠纪层序-古地理及聚煤规律[J].煤炭学报,2014,39(8):1725-1734.
SHAO Longyi,DONG Daxiao,LI Mingpei,et al.Sequence paleogeography and coal accumulation of the Carboniferous-Permian in North China basin[J].Journal of China Coal Society,2014,39(8):1725-1734.
[22] 杨起,吴冲龙,汤达祯,等.中国煤变质作用[J].地球科学-中国地质大学学报,1996,21(3):311-319.
YANG Qi,WU Chonglong,TANG Dazhen,et al.Coal metamorphism in China[J].Earth Science-Journal of China University of Geoscience,1996,21(3):311-319.
[23] KETRIS M P,YUDOVICH Y E.Estimations of Clarkes for carbonaceous biolithes:world average for trace element contents in black shales and coals[J].International Journal of Coal Geology,2009,78: 135-148.
[24] TAYLOR S R,MCLENNAN S M,ARMSTRONG R L,et al.The composition and evolution of the continental crust:rare earth element evidence from sedimentary rocks and discussion[J].Philosophical Transactions of the Royal Society A:Mathematical,Physical and Engineering Sciences,1981,301(1461):381-399.
[25] DAI Shifeng,JIANG Y,WARD C R,et al.Mineralogical and geochemical compositions of the coal in the Guanbanwusu Mine,INNER Mongolia,China:Further evidence for the existence of an Al(Ga and REE) ore deposit in the Jungar Coalfield[J].International Journal of Coal Geology,2012,98:10-40.
[26] SUN Yuzhuang,ZHAO Cunliang,ZHANG Jianya,et al.Concentrations of valuable elements of the coals from the Pingshuo Mining District,Ningwu Coalfield,northern China[J].Energy,Exploration & Exploitation,2013,31(5):727-744.
[27] 孙玉壮,赵存良,李彦恒,等.煤中某些伴生金属元素的综合利用指标探讨[J].煤炭学报,2014,39(4):744-748.
SUN,Yuzhuang,ZHAO Cunliang,LI Yanheng,et al.Minimum mining grade of the selected trace elements in Chinese coal[J].Journal of China Coal Society,2014,39(4):744-748.
[28] GRIGORIEV N A.Chemical element distribution in the Upper ContinentaL Crust[M].UBRAS,Ekaterinburg,2009:382.
[29] DAI Shifeng,GRAHAM I T,WARD C R.A review of anomalous rare earth elements and yttrium in coal[J].International Journal of Coal Geology,2016,159(4):82-95.
[30] AMEH E G.Geochemistry and multivariate statistical evaluation of major oxides,trace and rare earth elements in coal occurrences and deposits around Kogi east,Northern Anambra Basin,Nigeria[J].International Journal of Coal Science & Technology,2019,6(2):260-273.
[31] 刘贝,黄文辉,敖卫华,等.沁水盆地晚古生代煤中稀土元素地球化学特征[J].煤炭学报,2015,40(12):2916-2926.
LIU Bei,HUANG Wenhui1,AO Weihua,et al.Geochemistry characteristics of rare earth elements in the late Paleozoic coal from Qinshui Basin[J].Journal of China Coal Society,2015,40(12):2916-2926.
[32] DAI Shifeng,JIANG Yaofa,WARD C R,et al.Mineralogical and geochemical compositions of the coal in the Guanbanwusu Mine,Inner Mongolia,China:Further evidence for the existence of an Al(Ga and REE) ore deposit in the Jungar Coalfield[J].International Journal of Coal Geology,2012,98(3):10-40.
[33] 秦身钧,高康,陆青锋,等.煤中锂的研究进展[J].吉林大学学报(地球科学版),2015,45(S1):1-2.
QIN Shenjun,GAO Kang,LU Qingfeng,et al.Research progress of lithium in coal[J].Journal of Jilin University(Earth Science Edition),2015,45(S1):1-2.
[34] BAI Xiangfei,WANG Yue,LI Wenhua.Distribution and occurrence of trace elements in the No.14 coal from the Huolinhe mine[J].International Journal of Coal Science & Technology,2017,4(3):199-213.
[35] LEWINSKA-PREIS L,FABIANSKA M J,CMIEL S,et al.Geochemical distribution of trace elements in Kaffioyra and Longyearbyen coals,Spitsbergen,Norway[J].International Journal of Coal Geology,2009,80:211-223.
[36] 代世峰,任徳贻,周义平,等.煤型稀有金属矿床:成因类型、赋存状态和利用评价[J].煤炭学报,2014,39(8):1707-1715.
DAI Shifeng,REN Deyi,ZHOU Yiping,et al.Coal-hosted rare metal deposits:Genetic types,modes of occurrence,and utilization evaluation[J].Journal of China Coal Society,2014,39(8):1707-1715.
[37] WANG Wenfeng,QIN Yong,SANG Shuxun,et al.Geochemistry of rare earth elements in a marine influenced coal and its organic solvent extracts from the Antaibao mining district,Shanxi,China[J].International Journal of Coal Geology,2008,76(4):309-317.
[38] LIU Zhifei,WEI Yingchun,NING Shuzheng,et al.The differences of element geochemical characteristics of the main coal seams in the Ningdong coalfeld,Ordos Basin[J].Journal of Geochemical Exploration,2019,202:77-91.
[39] 郑刘根,刘桂建,张浩原,等.淮北煤田二叠纪煤中稀土元素地球化学研究[J].高校地质学报,2006,12(1):41-52.
ZHENG Liugen,LIU Guijian,ZHANG Haoyuan,et al.Study on Geochemistry of rare earth elements( REEs) in Permian coal from Huaibei coalfield[J].Geological Journal of China Universities,2006,12(1):41-52.