INVESTIGATION OF THE HIGH-TEMPERATURE BEHAVIOR OF COAL ASH IN REDUCING AND OXIDIZING ATMOSPHERES
INVESTIGATION OF THE HIGH-TEMPERATURE BEHAVIOR OF COAL ASH IN REDUCING AND OXIDIZING ATMOSPHERES
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DOI：
10.1016/0016-2361(81)90158-7
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发表时间：
1981-01-01
期刊：
影响因子：
7.4
通讯作者：
DUNMYRE, GR
中科院分区：
文献类型：
--
作者：
HUFFMAN, GP;HUGGINS, FE;DUNMYRE, GR
研究了一组煤所产生的灰的高温特性，这些煤具有广泛的矿物学特征。采用Mössbauer光谱、扫描电子显微镜(SEM)/自动图像分析（AIA）和x射线衍射（XRD）对还原（60% CO/40% CO2）和氧化（空气）气氛下不同温度淬火的灰分样品进行了物相分析。研究发现，在低于ASTM灰锥熔合试验定义的初始变形温度（IDT） 200-400℃的温度下，灰发生了明显的部分熔化。在还原条件下，熔化速度大大加快，在900 ~ 1100℃之间，熔化灰的比例迅速增加，在≈1200℃以上达到饱和。在900 ~ 1200℃淬火的样品中，观察到浮士体（FeO）、铁矾体（Fe2SiO4）、海尖晶石（FeAl2O4）和含铁玻璃等相，表明在还原性气氛中，灰的熔化通常受FeO- al2o3 - sio2相图中富铁角的控制。富含CaS的灰烬是这个规则的一个例外，因为形成了大量的硫化铁，熔化行为部分由FeO-FeS相图控制。在氧化条件下，钾似乎是最重要的低温助熔剂元素，因为在1100℃至1200℃以下淬火的样品中玻璃的百分比与煤中含钾矿物伊利石的量成正比。在1200°C以上的空气中，钙和铁（在较小程度上）成为有效的助熔剂元素；融化在1200至1400℃之间加速，在1400至1500℃之间，大多数灰烬接近完成。为了延缓灰分的熔化，一般认为铝是灰分中最理想的成分，而铁、钙和钾是最不理想的成分。
The high-temperature behaviour of ashes from a suite of coals exhibiting a wide range of mineralogies has been investigated. Phase analysis of ash samples quenched from various temperatures under either a reducing (60% CO/40% CO2) or an oxidizing (air) atmosphere was performed by Mössbauer spectroscopy, scanning electron microscopy (SEM)/automatic image analysis (AIA), and X-ray diffraction (XRD). It was found that significant partial melting of the ashes occurred at temperatures as low as 200–400 °C below the initial deformation temperature (IDT) defined by the ASTM ash cone fusion test. Melting was greatly accelerated under reducing conditions, for which the percentage of melted ash increased rapidly between 900 and 1100 °C, saturating at temperatures above ≈ 1200 °C. The observation of such phases as wustite (FeO), fayalite (Fe2SiO4), hercynite (FeAl2O4), and ferrous glass in samples quenched from 900 to 1200 °C indicates that ash melting in a reducing atmosphere is usually controlled by the iron-rich corner of the FeO-Al2O3-SiO2phase diagram. Ashes rich in CaS are an exception to this rule, for large quantities of iron sulphide are formed and the melting behaviour is controlled in part by the FeO-FeS phase diagram. Under oxidizing conditions, potassium appears to be the most important low-temperature fluxing element, as the percentage of glass in samples quenched from temperatures below 1100 to 1200 °C was proportional to the amount of the potassium-bearing mineral illite contained in the coal. Above 1200 °C in air, calcium and, to a lesser extent, iron became effective as fluxing elements; melting accelerated between 1200 and 1400 °C, and was near completion between 1400 and 1500 °C for most ashes. To retard ash melting, it is generally concluded that aluminium is the most desirable constituent of ash, whereas the most undesirable constituents are iron, calcium, and potassium.