Distribution of rare earth elements in PM10 emitted from burning coals and soil-mixed coal briquettes

Emission from burning coals is one of the major sources of the airborne particles in China.We carried out a study on the rare earth elements(REEs)in the inhalable particulate matter(PM10)emitted from burning coals and soil-coal honeycomb briquettes with different volatile contents and ash yields in a combustion-dilution system.Gravimetric analysis indicates that the equivalent mass concentration of the PM10 emitted from burning the coals is higher than that emitted from burning the briquettes.The ICP-MS analysis indicates that the contents of total REEs in the coal-burning PM10 are lower than those in the briquetteburning PM10.In addition,the contents of the light rare earth elements(LREEs)are higher than those of the heavy rare earth elements(HREEs)in the PM10 emitted from burning the coals and briquettes,demonstrating that the REEs in both the coal-burning and briquetteburning PM10 are dominated by LREEs.The higher contents of total REEs and LREEs in the coal-burning PM10 are associated with the higher ash yields and lower volatile contents in the raw coals.A comparative analysis indicates that the La/Sm ratios in the PM10 emitted from burning the coals and briquettes,being lower than 2,are lower than those in the particles from gasoline-powered vehicle emission.

土壤修复中固液混合过程的研究及应用

以土壤修复中淋洗混合过程为研究目标,使用自有设备开展了液固混合过程实验,以混合效果和单位质量能耗为目标函数,以混合比例、搅拌桨形式、搅拌转速以及搅拌时间等操作参数为考察变量,通过设计均匀实验,并利用DPS软件对实验结果进行数据处理,并经过实验验证,得到最优固液混合操作条件为搅拌桨类型为铲式,液固混合质量比为0.5,搅拌速度为70 r/min,搅拌时间为10 min,得到的平均混合度为0.94,单位质量物系功耗为12.1 kg/kJ。