我国的能源结构是富煤贫油少气，煤炭的高效合理利用就成为国家能源开发利用过程中的重点。在煤炭开发利用过程中，锅炉结渣问题一直是一个难题，会影响锅炉的安全经济运行，而煤灰的熔融特性与锅炉结渣的关系密切，因此对煤灰熔融特性的研究就变得非常重要。 本文以宁煤梅花井沫煤煤灰为研究对象，通过添加SiO2、Al2O3、CaO、Fe2O3、MgO等氧化物来研究氧化物对宁煤煤灰熔融温度的影响以及煤灰熔融温度的变化规律，采用X-射线衍射的方法分析煤灰的矿物组成，根据煤灰中矿物质的变化规律分析反应机理，从而得到宁煤煤灰熔融特性的变化规律。 实验研究表明： 1、宁煤煤灰DT=1119℃、ST=1137℃、HT=1150℃、FT=1210℃，属易熔灰。从化学组成分析，主要原因是Fe2O3和CaO的含量较多；从矿物组成分析，主要是因为煤灰中存在铁尖晶石、铁堇青石等含铁矿物以及钙硅石、斜硅钙石等含钙矿物，这些矿物属于易熔矿物，具有降低煤灰熔融温度的作用。 2、SiO2和Al2O3属于酸性氧化物，总体上能够提高煤灰熔融温度。游离SiO2的存在导致煤灰熔融温度快速升高，Al2O3在煤灰中属于起“骨架”作用的耐熔组分，高含量的Al2O3导致煤灰熔融温度升高。 XRD分析结果表明：当SiO2百分含量为74%时，煤灰中含有石英、红柱石和莫来石等高熔点矿物以及SiO2无定型玻璃体，这些物质有利于升高宁煤煤灰熔融温度；当Al2O3百分含量为39%时，高温时大量的金刚砂的存在有效提高了煤灰的熔融温度。 3、CaO、Fe2O3和MgO属于碱性氧化物，随着这三种氧化物含量的增加，宁煤煤灰熔融温度的变化趋势都是先降低后升高，分别当CaO质量分数为25%，Fe2O3质量分数为35%，MgO质量分数为6%时，煤灰熔融温度最低。 XRD分析结果表明：对于CaO而言，钙黄长石、钙长石和硅钙石等高含钙化合物之间会发生低温共熔现象，从而导致煤灰熔融温度明显下降；对于Fe2O3而言，其还原得到的FeO可以与煤灰中的很多成分发生反应，导致一些高熔点矿物减少，生成了铁尖晶石，斜铁辉石等易熔矿物，同时铁尖晶石和斜铁辉石之间还会发生低温共熔，总的来说，高熔点矿物的减少、易熔矿物的生成以及低温共熔现象的发生共同导致煤灰熔融温度降低；对于MgO而言，Mg2+的存在促使石英与莫来石等一些高熔点矿物发生反应生成假蓝宝石和堇青石，这些碱性矿物的低熔点是导致煤灰熔融温度降低的主要原因。总的来说，向宁煤煤灰中加入CaO、Fe2O3和MgO等碱性氧化物后，高熔点矿物的减少和消失使煤灰缺少了骨架矿物的支撑，生成了助熔矿物的同时还伴随有低温共熔现象，这些因素综合降低了宁煤煤灰的熔融温度。 4、本研究得出的加入氧化物后宁煤煤灰熔融特性的变化规律对工业生产有一定的理论指导意义。当采用固态排渣方式排渣时，可以向煤灰中加入SiO2和Al2O3等酸性氧化物，从而提高煤灰熔融温度，使煤灰熔融温度高于操作温度；当采用液态排渣方式排渣时，可以向煤灰中加入CaO、Fe2O3和MgO等碱性氧化物，从而降低煤灰熔融温度，使煤灰熔融温度低于操作温度。

The energy structure of China is rich in coal and lean in oil and gas, so efficient and rational use of coal becomes the focus of development and utilization of energy. Boiler slagging issue has been a problem in the process of development and utilization of coal. It affects the safe operation of the boiler and is closely related to the melting characteristics of coal ash, so the study of coal ash fusibility becomes very important. In this paper, I take Ningxia coal ash as the research object and study the variational law of Ningxia coal ash fusion temperature by adding SiO2, Al2O3, CaO, Fe2O3, MgO. I use X-ray diffraction method to analysis the mineral composition of the coal ash. I analysis the reaction mechanism and the variational law of Ningxia coal ash fusibility according to the variational law of minerals in the coal ash. Experimental studies have shown that: 1. Ningxia coal ash fusion temperature: DT = 1119℃, ST = 1137℃, HT = 1150℃, FT = 1210℃, Ningxia coal ash is fusible ash. Analysis of chemical composition, mainly because the content of Fe2O3 and CaO is high; Analysis of mineral composition, mainly because Ningxia coal ash contains minerals such as hercynite, sekaninaite which are rich in iron and wollastonite, kilchoanite which are rich in calcium. The presence of fusible minerals leads to low ash fusion temperature. 2. SiO2 and Al2O3 are acidic oxides, which can increase ash fusion temperature. SiO2 amorphous vitreous and the presence of free SiO2 lead to a rapid increase of ash fusion temperature, Al2O3 is refractory component which acts as the "skeleton" in the ash. High content of Al2O3 results in high ash fusion temperature. XRD analysis shows that: When the percentage content of SiO2 is 74%, the minerals with high melting point such as quartz, andalusite and mullite and SiO2 amorphous vitreous mineral have a beneficial increase in Ningxia coal ash fusion temperature; When the percentage content of Al2O3 is 39%, a large number of diamond generates because of the high content of Al2O3 which results in high ash fusion temperature. 3. CaO, Fe2O3 and MgO are alkaline oxides. The variational tendency of Ningxia coal ash fusion temperature are all first rise and then decrease as the content of these three oxides increase. The ash fusion temperature is lowest respectively when the mass fraction of CaO is 25% , the mass fraction of Fe2O3 is 35%, the mass fraction of MgO is 6%. XRD analysis shows that: for CaO, the minerals that contain rich calcium such as gehlenite, anorthite and wollastonite may occur low temperature eutectic phenomenon which results in low ash fusion temperature; for Fe2O3, FeO can react with many components of coal ash which reducts some refractory minerals and generates fusible minerals such as ferrosilite and hercynite, these fusible minerals may occur low temperature eutectic phenomenon, they all cause lower ash fusion temperature; for MgO, Mg2+ prompts quartz to react with some refractory minerals such as mullite and generates sapphirine and cordierite, these alkaline minerals result in low ash fusion temperature. In general, when we add CaO, Fe2O3, and MgO into Ningxia coal ash, the reduction and disappearance of refractory minerals make coal ash lack support of skeleton minerals, generate fluxing minerals and accompanied by low temperature eutectic phenomenon, these factors all reduce Ningxia coal ash fusion temperature. 4. The study obtains Ningxia coal ash fusibility variation, it has certain theoretical guiding significance for industrial production. We can add SiO2 and Al2O3 into Ningxia coal ash, thus improve ash fusion temperature and make the ash fusion temperature higher than the operating temperature when using solid state slag. We can add CaO, Fe2O3 and MgO into Ningxia coal ash, thus reduce ash fusion temperature and make the ash fusion temperature lower than the operating temperature when using liquid state slag.