粉煤灰基充填膏体制备过程中氨气释放的超声强化特性

Ultrasonic strengthening characteristics of ammonia release during the preparation of fly ash based filling paste

将粉煤灰作为主要胶凝材料的膏体充填开采不仅能有效控制地面沉降、解决“三下”压煤问题、提高煤炭采出率,还可解决燃煤电厂粉煤灰堆积难题。而粉煤灰基充填膏体的氨气释放会对充填作业面的气体环境造成污染,亟需治理。提出一种利用超声波促进膏体氨气释放的新思路。通过对粉煤灰浆液进行超声处理,采用以超声时长(A)、超声功率(B)、固液比(C)作为考察因素,进行单因素实验,结果表明:随着超声时长、超声功率以及固液比的的增加氨气释放速率呈现出先增大后减小的趋势,并在超声时长、超声功率以及固液比分别为30 min、80 W和1∶10时达到最大值。在单因素实验结果的基础上进行响应面实验建立回归模型。通过响应面优化确定最佳实验参数。结果表明:影响因素主次顺序为:A>B>C,AB>AC>BC;去除氨气最佳实验参数为:超声时长为32 min,超声功率为80 W,固液比为1∶7.7。验证结果表明:实测值与预测值仅存在-1.6%的相对误差。利用优化后的实验参数处理粉煤灰,并制备成充填膏体测定氨气释放量,发现膏体氨气释放量平均减少了95.94%,氨气释放速率提高84.02%,膏体3 d和28 d的单轴抗压强度分别提高185.00%和86.50%,坍塌度、泌水率和凝结时间均降低,同时减少了膏体内部多害孔数量,使孔隙率由33.58%降低到28.13%,为粉煤灰基充填膏体的氨气释放治理提供新的方法与思路。

Fly ash-based paste-filling mining can not only effectively control land subsidence and increase the coal recovery rate,but it also solves the problem of fly ash accumulation in coal-fired power plants.The release of ammonia from fly ash-based filling paste contaminates the air environment of the coal mine filling face,necessitating immediate remediation.This study proposes a new method of using ultrasound to promote the release of paste ammonia.Through the ultrasonic treatment of fly ash slurry,the ultrasonic time(A),ultrasonic power(B)and solid-liquid ratio(C)are used as investigation factors.The results show that the ammonia release rate increases first and then decreases with the increase of ultrasonic time,ultrasonic power and solid-liquid ratio,and reaches the maximum when the ultrasonic time,ultrasonic power and sol-id-liquid ratio are 30 min,80 W and 1∶10,respectively.The response surface experiment is conducted on the basis of single factor test to establish a regression model.The optimal experimental parameters are determined by response surface optimization.The results show that the order of influencing factors is:A>B>C,AB>AC>BC.The optimum experi-mental parameters for ammonia removal are as follows:ultrasonic time is 32 min,ultrasonic power is 80 W,and solid-li-quid ratio is 1∶7.7.Through verification,it is found that there is only a relative error of−1.6%between the measured value and the predicted value.The optimized experimental parameters are used to treat the fly ash to prepare the filling paste to determine the ammonia release amount.It is found that the ammonia release amount of the paste is reduced by 95.94%.The ammonia release rate increases by 84.02%,and the uniaxial compressive strength of the paste at 3 d and 28 d increases by 185.00%and 86.50%,respectively.The slump,bleeding rate and setting time are decreased,and the number of harmful pores in the paste is reduced,so that the porosity is decreased from 33.58%to 28.13%.It provides a new meth-od for the ammonia release treatment of the fly ash-based filling paste.