煤体瓦斯放散磁场响应特征

Magnetic field response of the characteristics of coal gas emission

针对含煤体瓦斯放散磁效应特性,建立瓦斯放散磁效应实验系统,测试磁化与未磁化煤样瓦斯放散过程,研究恒定磁场对煤样放散瓦斯的影响。实验结果表明:放散初速度较小(f值越大),磁化后煤样瓦斯放散有明显减小趋势;放散初速度越大(f值越小),磁化后煤样瓦斯放散略有增大的趋势;且两者的变化程度都受磁化时间的影响,在撤掉磁场时Δp并未回落至初始值,并保持一定的时间记忆效应。其机理是f值大的煤样,磁化后b值减小,随着压力的升高,磁化后煤样的表面能降低值都小于未磁化的煤样,说明在加磁后煤体吸附容纳瓦斯的空间减少使得吸附量减少,产生的瞬时瓦斯压力梯度降低,从而使得瓦斯的放散初速度降低,而对于坚固性系数f值小的煤样有相反的实验结果。

Based on magnetic effect characteristics of coal gas emission,by establishing experimental system of the gas emission magnetic effect,the emission process of unmagnetized and magnetized coal sample gas is tested and the influence of constant magnetic field on the coal sample emission gas is studied.The initial experimental data shows that the smaller initial emission rate of gas is（the value of fis large）,the smallercoal simple gas emission will be;otherwise,the larger initial emission rate of gas is（the value of fis small）,the larger coal simple gas emission will be.Both of them are affected by magneted time.When the magnetic field is removed,Δp does not restore to the original value immediately and maintains a certain amount of time.The preliminary study on its mechanism shows that the b value of the samples with large f values decreases after magnetization.With the voltage increases,the surface lowering values of magneted samples are lower than those of unmagneted ones.Namely under the action of magnetization,the reduce of gas adsorption space reduces the adsorption quantity,and the instantaneous gas pressure gradient decreases,so as to slow the gas radiation initial speed.However,small fvalue has opposite results.