研究不同密度准东高铁煤灰熔融特性,可探究准东高铁煤灰不均匀熔融规律。用有机重液浮沉法分离准东高铁煤不同密度组分,测定各煤样低温灰化后矿物组成及煤灰化学组成、熔融温度,经XRD和SEM-EDS分析熔融灰矿物组成、微观形貌和元素分布。发现准东高铁煤分离出不同密度组分主要分布于1.4~1.5g/cm3,占51.79%,煤中铁赋存形态主要为硫铁矿及少量菱铁矿;煤灰中元素不同,分离出组分密度也不同,且随Fe元素含量增加煤样组分密度增大,在密度组分>1.5g/cm3的制备煤灰中Fe元素质量分数达67.50%;各组分灰成分差异大,煤中Fe是影响熔点主要因素之一,可显著降低整体煤灰熔融温度;结合高温灰样XRD与SEM-EDS分析,不同密度组分中钙铝黄长石含量增加是导致灰熔融温度增加的原因;Fe、Mg主要富集于轮廓较明显块状灰颗粒,Si和Ca主要富集于熔融区域,且随密度增大块状颗粒含量增多;块状灰颗粒矿物主要为镁铁氧化物和赤铁矿,熔融区域矿物主要为钙铝黄长石,在1300℃煤灰中熔融区域与块状颗粒并未熔合,可知高铁煤中Fe主要存在于煤中外来矿物,且含钠矿物与钙铝黄长石发生低温共熔,熔融区域熔点降低。

Melting characteristics of different densities of Zhundong high-iron coal were studied and the uneven melting law of Zhundonghigh-iron coal was explored. The organic heavy liquid floatation sedimentation method was used to separate components of different densities from Zhundong high-iron coal. The mineral composition of each coal sample after low-temperature ashing, as well as the chemicalcomposition and melting temperature of coal ash were measured. The ash structure, element distribution and mineral composition were alsoanalyzed using XRD and SEM-EDS. The results show that Zhundong high-iron coal and its density components mainly distributes between1.4-1.5 g/ cm3,accounting for 51.79%, and the occurrence forms of iron in coal are mainly pyrite and a small amount of siderite. Thechange of elements in the coal ash leads to the change of the density of the separated components. With the increase of the elemental content of Fe, the density of the coal sample components increases, and in the prepared coal ash. With the density component exceeding1.5 g/ cm3, the elemental content of Fe reaches 67.50%. The ash composition of each density component varies greatly and Fe in the coalis one of the main factors affecting the melting point, which can significantly reduce the melting temperature of the overall coal ash. Combining XRD and SEM-EDS analysis of high-temperature ash samples, the increase of Gehlenite content in different density components isthe reason for the increase of ash melting point. Fe and Mg are mainly enriched in block shaped ash particles with clear contours, while Siand Ca are mainly enriched in the melting zone, and the content of block shaped particles increases with increasing density. It is speculated that the minerals of block shaped ash particles are mainly magnesium iron oxides and Hematite, and the minerals in the melting zoneare mainly Gehlenite. At 1 300 ℃ , the melting zone of coal ash does not melt together with the massive particles, indicating that Fe inhigh iron coal mainly exists in foreign minerals in the coal. Sodium containing minerals will undergo low-temperature co melting reactionswith Gehlenite, reducing the melting temperature of the melting zone.

0 引言

1 试验

   1.1 煤样

   1.2 煤样的浮沉分离

   1.3 煤样及煤灰性质分析

2 结果与讨论

   2.1 准东高铁煤密度分布

   2.2 准东高铁煤矿物组成和化学组成

   2.3 准东高铁煤不同密度组分灰熔融温度

   2.4 准东高铁煤不同密度组分灰熔融微观形貌

3 结论