Evaluation of Static Acid Production Potential for Coal Bearing Formation
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摘要: 岩石静态产酸评价对于矿山酸性水防治具有重要的指导意义, 但传统的岩石静态产酸评价方法无法准确地评价复杂岩石样品.通过对山西省西山煤田石炭二叠纪含煤岩系12个岩石样品产酸潜力的评价找出了影响复杂岩石样品产酸潜力评价准确性的关键指标, 并建立了适合复杂岩石样品的评价方法.研究结果表明, 净产酸潜力(NAPP)、酸中和潜力(ANC)与最大产酸潜力(MPA)的比值是产酸潜力评价的关键指标, 根据这2个指标建立的产酸评价分区方法能够准确评价NAPP绝对值较小(＜50 kg·t-1)的复杂岩石样品的产酸潜力; 复杂岩石样品的矿物学信息能够反映样品长期的产酸潜力, 通过分析碳酸盐矿物总含量与黄铁矿含量的比值能够提高复杂岩石样品的产酸潜力评价精度; 样品糊状物的pH值(Paste pH)只能反映岩石样品中已储存酸碱度信息, 可作为岩石产酸潜力评价的参考指标.结合西山煤田典型矿井水水质特征, 进一步验证了岩石产酸潜力综合评价的准确性.Abstract: Static acid production potential (APP) evaluation is useful to acid mine drainage control, but traditional APP evaluation methods can not accurately evaluate complex rock samples. In this study, key indexes of APP evaluation are found and a new APP evaluation method is established for complex rock samples through evaluating APP of twelve typical rock samples in Permo-Carboniferous coal-bearing measures from Xishan coalfield in Shanxi Province. It is demonstrated that net acid production potential (NAPP), the ratio of acid neutralization capacity (ANC) to maximal potential of acidity (MPA) are the most important indexes of APP evaluation. The complex rock samples with little NAPP absolute value (< 50 kg·t-1) can be accurately evaluated using the above two key indexes. Mineralogical information can reflect long term APP of complex rock samples. App evaluation precision of complex rock samples is improved through analyzing the ratio of total content of carbonate minerals to pyrite content. It is shown that Paste pH can only reflect natural acidity-alkalinity of rock samples. Therefore, Paste pH can not be used as a key index for APP evaluation. The accuracy of static acid production potential evaluation methods is further validated through comparing typical mine drainage characteristics in Xishan coalfield.
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图 1 根据岩石样品的总硫百分含量和Paste pH值划分的产酸潜力评价区
Fig. 1. Classification of acid production potential of rock samples based on Paste pH and Stotal
图 2 根据岩石样品的NAPP值和Paste pH值划分的产酸潜力评价区
Fig. 2. Classification of acid production potential of rock samples based on Paste pH and NAPP
图 3 根据岩石样品的ANC值和MPA值划分的产酸潜力评价分区
Fig. 3. Classification of acid production potential of rock samples based on MPA and ANC
图 4 根据岩石样品的NAPP值和ANC/MPA比值划分的产酸潜力评价分区
Fig. 4. Classification of acid production potential of rock samples based on ANC/MPA and NAPP
表 1 岩石样品的Paste pH、MPA、ANC和NAPP值(kg·t-1)
Table 1. The value of Paste pH, MPA, ANC and NAPP of rock samples (kg·t-1)
样品编号 Paste pH MPA ANC NAPP ANC/MPA GD-P-6 5.00 1 191.60 -4.45 1 191.60 0.00 ML-P-6 2.75 647.80 -11.24 647.80 -0.02 GD-M-2 6.15 32.28 4.24 28.04 0.13 ML-M-5 4.00 25.70 -1.65 25.70 -0.06 ML-S-2 8.85 3.06 9.73 -6.67 3.18 ML-M-3 8.70 7.04 14.98 -7.94 2.13 ML-B-1 8.67 0.09 29.76 -29.67 331.00 GD-M-3 8.51 13.77 43.88 -30.11 3.19 GD-I-5 7.67 144.70 192.6 -47.90 1.33 GD-S-1 8.42 0.89 119.8 -118.90 135.00 ML-L-4 7.94 21.11 671 -649.90 31.80 GD-L-4 7.87 6.73 957.03 -950.30 142.00 
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表 2 岩石样品的矿物组成定量分析结果(%)、NAPP值(kg·t-1)和ANC/MPA比值
Table 2. Mineral species and percentage content (%), NAPP value and ANC/MPA ratio of rock samples
样品编号 粘土矿物 石英 斜长石 方解石 铁白云石 菱铁矿 黄铁矿 NAPP ANC/MPA GD-M-2 61.8 34.0 4.2 28.04 0.13 ML-M-5 65.9 30.8 3.3 25.70 0.00 ML-S-2 56.3 40.6 1.8 1.3 -6.67 3.18 ML-M-3 66.6 27.0 3.9 2.5 -7.94 2.13 ML-B-1 94.1 4.6 0.9 0.4 -29.67 331.00 GD-M-3 41.6 39.3 4.4 12.7 2.0 -30.11 3.18 GD-I-5 0.7 26.2 65.9 7.2 -47.90 1.33
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表 3 岩石样品的最终产酸潜力评价结果
Table 3. Final results of acid production potential evaluation of rock samples
样品编号 岩性 评价结果 ML-B-1 铝土泥岩 不产酸 ML-S-2 砂岩 不产酸 ML-L-4 灰岩 不产酸 ML-M-3 泥岩 不确定 ML-M-5 泥岩 弱产酸 ML-P-6 含杂质黄铁矿 强产酸 GD-S-1 砂岩 不产酸 GD-M-3 泥岩 不产酸 GD-L-4 灰岩 不产酸 GD-I-5 含杂质菱铁矿 不产酸 GD-M-2 泥岩 弱产酸 GD-P-6 含杂质黄铁矿 强产酸
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表 4 西山煤田典型矿井水水质指标
Table 4. Chemical parameters of typical mine water in Xishan coalfield
采样编号 2SL 2LY 2KJ 8HY 8KJ 采样层位 2号煤层上部砂岩裂隙水 2号煤层老窑积水 2号煤层矿井水 8号煤层顶板灰岩水 8号煤层矿井水 岩石类型 泥岩、砂岩 泥岩、砂岩、黄铁矿 泥岩、砂岩、黄铁矿 灰岩 灰岩、砂岩、黄铁矿 水质类型 HCO3-Ca SO4-Na SO4-Ca HCO3-Na HCO3-Na·Ca pH 7.50 2.38 4.83 8.46 7.89 Cl- 13.16 38.60 21.00 68.20 36.60 SO42- 34.98 3 486.00 2 726.00 3.70 11.00 HCO3- 211.00 - - 471.00 349.00 CO32- - - - 18.60 - NO3- 7.08 - - 0.21 - K+ 2.31 68.70 10.60 16.30 5.28 Na+ 28.58 629.30 58.90 214.50 45.50 Ca2+ 41.89 474.10 543.00 3.49 44.30 Mg2+ 14.33 111.90 266.00 1.51 27.60 Fe3+ - 140.80 102.90 0.02 - 注：-表示未检测出；水质指标单位为mg/L.
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[1] Bell, F.G., Bullock, S.E.T., 1996. The Problem of Acid Mine Drainage, with an Illustrative Case History. Environmental & Engineering Geoscience, 2: 369-392. doi: 10.1144/1470-9236/00121 [2] Blodau, C., 2006. A Review of Acidity Generation and Consumption in Acidic Coal Mine Lakes and Their Watersheds. Science of the Total Environment, 369(1-3): 307-332. doi: 10.1016/j.scitotenv.2006.05.004 [3]