地下铀矿山留矿法采场受限空间内氡迁移的数值模拟

为研究铀矿山留矿法采场氡迁移规律,依据留矿法采场的构造和物理几何尺寸,建立了受限空间内颗粒堆积型射气介质气体流动的数学模型和氡迁移方程,以10 m和20 m高爆破矿堆为对象,采用计算流体力学(CFD)方法,研究了不同通风条件下采场中氡的迁移规律。结果表明:1)采场下行通风方式降低矿堆上部作业空间氡浓度的效果优于上行通风方式,但对采场运输巷道氡浓度的效果相反;采场排风氡浓度与采场通风风量成反比,氡析出份额与通风风量成正比;2)在相同通风风量下,10 m高爆破矿堆与20 m高爆破矿堆氡析出份额之差随通风风流量增长而逐渐缩小;3)均压通风对渗透率高(k=1×10-8m2)的采场排风氡浓度、矿堆氡析出份额有明显影响。

Numerical simulation for radon migration in the confined space of shrinkage mining stope of the underground uranium mine

To trace and identify the radon migration regularity in the shrinkage stope of the uranium mine so as to be able to pro vide a basis for the ventilation system design in accordance with the actual situation,the present paper has established a mathematical gas flow model and mathematical radon migration equations for the particle-packing emanation media in the confined space by taking the blasted ore heap of 10 m and 20 m as a case study sample.To achieve the purpose,we have,first of all,traced and identified the process of the radon production in the ore heap and its decay in the mining site by writing a UDF function in the Fluent software on the computational fluid dynamics (CFD) method.And,then,a simulated study has been done for the radon migration process in the confined space of the stope by changing such parameters as the wind flow,the heap height and its permeability.And,finally,we have also studied the impacts of the different ventilation parameters on the effect of the radon emissions and their control according to the simulation results of the radon exhaust concentration and its exhalation portion inside the mining space.The results of our investigation and examination show that:(1) To reduce the effect of the radon concentration in the upper working space of the ore heap,it is recommended to adopt the ascentional ventilation method instead of the descention al one.Nevertheless,the situation would be on the contrarary to the transportation roadways,for the radon concentration stands inversely proportional to the ventilation volume in the stope with its share of radon being proportional to the amount of the ventilation;(2) The difference of the radon exhalation portion between the heights of 10 m and 20 m of the mine tends to get gradually reduced with the increase of the ventilation flowing rate in the same ventilation volume on the condition when the permeability remains merely 10-9 m2;(3) The ventilation on the condition of equal pressure can actually have a significant effect on the radon exhalation concentration and its exhalation portion of the ore heaping on the condition that the stope is supposed to have a high permeability (say,k =1 × 10-8 m2).The radon exhalation portion can not be regarded as a constant on the condition that the gas exhaust and the radon exhalation portion in that blasting ore are somewhat under the control involved.However,when the ventilation parameters are laid out directly,it is necessary to take into account the effects of the ventilation method,the air volume and the permeability on the radon migration in the stope.