含Na矿物的生成机制探究

Formation mechanism of sodium-containing minerals

准东煤储量丰富,但其中高含量的Na制约了准东煤的大规模利用,前人针对准东煤中Na的处理方法进行了大量研究,但大多针对较低温度情况及Na的迁移转化特性,对于高温下霞石等含Na矿物的生成机理和其Na保持率尚不明确。在管式炉700~1400℃研究高岭土等硅铝矿物与Na反应生成含Na矿物的机制。结果表明:高岭土与Na的反应活性高于二氧化硅和氧化铝混合添加剂,生成霞石的温度更低,但无法在高温下稳定存在,Na保持率最高可达81.54%;NaSiAl样在800~1400℃下均能将Na以霞石的形式固定在样品中,Na保持率最高可达69.73%;熵产率发生突跃的温度段反映了系统的结构变化,熵产率一阶导数为零的切点预示反应的平衡点。

The reserve of Zhundong coal is abundant,but the high content of sodium restricts the large-scale utilization of Zhundong coal.The predecessors have studied a lot of methods for the treatment of sodium in Zhundong coal,but most of the studies are aimed at the situation at lower temperatures and the migration and transformation characteristics of sodium.The formation mechanism of sodium-containing minerals such as nepheline at high temperature and their sodium retention rate are still unclear.The mechanism of the reaction between kaolin,other silica-alumina minerals and sodium to form sodium-containing minerals was studied by using a tube furnace experimental bench in the temperature range of 700-1400℃.The results show that the reactivity of kaolin with Na is higher than that of the mixed additives of silica and alumina,the temperature of nepheline formation is lower,but it cannot exist stably at high temperature,and the sodium retention rate can reach up to 81.54%;The reactivity of NaSiAl sample is slightly lower,but sodium can be fixed in the sample in the form of nepheline at 800-1400℃,and the sodium retention rate sample can reach 69.73%;The temperature segment at which the entropy yield jumps abruptly reflects the structural change of the system,and the point where the first derivative of the entropy yield is zero indicates the equilibrium point of the reaction.