助熔剂对皖北刘桥二矿煤灰熔融特性的影响

Effect of flux on the melting characteristics of coal ash for the Liuqiao No.2 Coal Mine

研究了钙基、镁基和铁基等3种助熔剂对皖北刘桥二矿煤(AQ)灰熔融特性的影响,在添加助熔剂前后在氢气和氮气的混合气氛下对AQ煤灰进行不同温度的热处理,对矿物组成进行了XRD分析。结果表明:导致AQ煤灰熔融温度高的主要原因是1000℃以上形成的莫来石引起的;加入钙基、镁基和铁基等助熔剂均可以降低AQ煤灰的熔融温度,当钙基助熔剂的添加量达到6.2%时(以煤基计),或镁基助熔剂的添加量达到2.8%时,或铁基助熔剂的添加量达到5.6%时,均可使AQ的煤灰流动温度降到1 350℃以下,满足Shell气化炉的液态排渣要求;在高温下助熔剂与煤灰中其他铝硅酸盐矿物发生反应,生成低温共熔化合物,从而使煤灰熔融温度明显下降。

The effect of flux on the melting characteristics of coal ash for the Liuqiao No. 2 Coal Mine in North Anhui Province （AQ） was investigated. The change of the compositions of mineral under various temperatures with the atmosphere of N2 and H2 mixture before and after adding flux into AQ was analyzed by XRD. The results show that mullite formed over 1 000 ℃ has an effect on increasing the ash fusion temperature of coal, and this is the major reason which leads to high ash fusion temperature of AQ. The coal ash fusion temperature is obviously reduced by adding calcium-based flux, magnesium-based flux and ferrum-based flux respectively. While the adding mass amount of calcium- based flux is 6. 2% （coal as reference）, or the adding mass amount of magnesium-based flux is 2. 8%, or the adding mass amount of ferrum-based flux is 5.6% ,the ash fusion temperature（TF） of AQ can be reduced to below 1 350℃ to meet the requirements of the shell gasifier slag-tapping process. The low temperature eutectic mixtures are easily formed between flux with aluminium silicate minerals under high temperature, which will remarkably decrease coal ash fusion temperature.