典型煤系岩石的可见-近红外光谱特征研究

Research on visible-near infrared spectrum features of typical coal measures rocks

为研究基于可见-近红外光谱技术的煤岩识别方法,从山西、山东4个煤矿收集了页岩、砂岩、灰岩三大类11种典型煤系岩石,测定了其可见-近红外波段(400～2 450nm)的反射光谱,分析了其矿物、元素组成对反射光谱特征的影响,获得了碳质物质含量对煤系页岩反射光谱曲线特征参数的影响规律。研究结果表明:①绝大多数煤系岩石的反射光谱曲线在可见光波段(400～780nm)和短波近红外波段(780～1 100nm)呈现出随波长增加的多重吸收谷。在长波近红外波段(1 100～2 450nm),明显的吸收谷主要集中在1 400,1 900,2 200,2 350nm波长,页岩、灰岩吸收谷的波长相对固定,而不同砂岩吸收谷的波长呈现出多种变化。②除碳质物质含量较高的碳质页岩外,同一煤矿各类煤系岩石与煤的可见-近红外波段反射光谱吸收特征差异明显。③当煤系页岩中碳质物质含量增大时,可见-近红外波段反射光谱曲线的光谱斜率和各明显吸收谷深度均呈先快速减小后趋于平缓的特点。

In order to study coal-rock identification method based on visible-near infrared spectrum technology, 11 types of typical coal measures rocks including three main categories namely shale, sandstone and limestone were collected from four coal mines of Shanxi and Shandong provinces. Their reflectance spectra in visible-near infrared band (400-2 450 nm) were measured and influences of mineral and elemental compositions on spectrum features were studied. Differences between reflectance spectrum curves of coal measures rocks and the ones of coals from the four coal mines were analyzed, and influence laws of carbonaceous matter content on characteristic parameters of reflectance spectra curves of coal measures shale were obtained. The study results show that reflectance spectrum curves of the most coal measures rocks show multiple absorption valleys with increasing wavelength in visible light band (400- 780 nm) and shortwave near infrared band (780-1 100 nm). In longwave near infrared band(1 100- 2 450 nm), distinct absorption valleys are mainly located near 1 400 nm, 1 900 nm, 2 200 nm and 2 350 nm wave length. The wave length of absorption valleys of shale and limestone are relatively fixed while the ones of different sandstones show a variety of changes.Except for carbonaceous shale without distinct absorption features, absorption features of reflectance spectra of coal measures rocks and coals from the same coal mine are obviously different in visible-near infrared band. With increase of carbonaceous matter content of coal measures shale, a common feature is presented that spectral slope of reflectance spectrum curves and depth of each distinct absorption valley in visible-near infrared band both decrease rapidly at first and then tend to be flat.