新疆淖毛湖煤田A4煤层优质直接液化用煤煤质特征与成因

新疆淖毛湖煤田A₄煤层具有优质的直接液化特性,以淖毛湖煤田A₄煤层为对象开展直接液化用煤研究,对优质直接液化用煤质量特征和成因认识具有重要意义。研究样品采集于淖毛湖煤田白石湖露天矿,测试结果显示淖毛湖煤田A₄煤层煤中各样品的氢碳原子平均值达0.94,挥发分产率平均达49.2%,直接液化的活性组分(镜质组+壳质组)含量高达97.7%,而A₄煤层灰分平均5.2%,灰分极低,且灰分中对直接加氢液化有不良影响的SiO₂和Al₂O₃质量分数较低,对液化有催化作用的Fe₂O₃质量分数较高。所以淖毛湖煤田煤岩煤质“三高一低”(高氢碳原子比、高挥发分及高活性组分、低灰分)的特征为直接液化带来了有利条件。淖毛湖煤样镜质组最大反射率平均值为0.42%,处在直接液化的最佳煤化阶段。煤相研究结果表明,淖毛湖煤田A₄煤层形成的早侏罗世八道湾组沉积所处的泥炭沼泽环境为富钙环境,保证了泥炭堆积早期的腐殖化作用和生物化学凝胶化作用,地层层序属于水进序列,能够很好的在泥炭堆积后迅速被上覆沉积物所覆盖,保证了泥炭处在缺氧的还原环境,使得凝胶化作用充分进行;同时,煤层上覆、下伏地层均隔水性良好,保证了煤岩组分的演化过程不易受到来自顶底板的富氧水的影响,上述因素,形成淖毛湖煤田煤超高的直接液化活性组分(镜质组+壳质组)的重要因素,为优质直接液化用煤形成提供了有利条件。

Characteristics and origin of high quality direct liquefaction coal of A4coal seam in Naomaohu coalfield,Xinjiang Province

The A₄coal seam of the Naomaohu coalfield in Xinjiang has a characteristic of high-quality for direct liquefaction by previous experiments.This research took the A₄coal seam of the Naomaohu coalfield as the object to carry out the study on coal for direct liquefaction,which is important for the quality characteristics and genetic understanding of the high-quality direct liquefaction coal.The research samples were collected at the Baishihu open-pit mine in the Naomaohu coalfield.The test results show that the average ratio of H/C in the A₄coal seam is 0.94,and the average volatile production rate is 49.2%.The active components of directly liquefied(vitrinite+chitin)content are as high as 97.7%,while the average ash content of A₄coal seam is 5.2%,which is extremely low,and the ash content has a low contents of SiO₂and Al₂O₃,which harm direct hydro liquefaction.The Fe₂O₃content has a higher value,which has a catalytic effect on liquefaction.Therefore,the characteristics of three high and one low coal quality(high H/C ratio,high volatile and high active components,and low ash content)of the Naomaohu coalfield have brought favorable conditions for the direct liquefaction process.The average maximum reflectance of the vitrinite group is 0.42%in the Naomaohu coal sample,which stays in the best coalification stage of direct liquefaction.The results of coal facies studies indicate that the early Jurassic Badaowan Formation deposits formed by the A₄coal seam in the Naomaohu coalfield are in a calcium-rich peat swamp environment,which ensures the early humification and biochemical gelation of peat accumulation.The stratigraphic sequence belongs to the water inlet sequence,which can be quickly covered by the overlying sediments after the peat is accumulated,ensuring that the peat stays in an oxygen-deficient and reducing environment so that the gelation is fully carried out.Meanwhile,the overlying and underlying strata have good water resistance,which ensures that the evolution process of maceral specification is not easily affected by the oxygen-rich water from the roof and floor.The above factors form the ultra-high direct liquefaction active component(vitrine of the Naomaohu coalfield).The important factors of the group(vitrinite and exinite group)provide favorable conditions to the formation of high-quality coal for direct liquefaction.