铀尾矿粒度分形分布对氡析出影响的初步研究

Preliminary Study on Influence of Fractal Size Distribution on Radon Emanation from Uranium Tailings

铀尾矿中氡的析出是备受重视的典型环境问题.本文实验研究了尾矿粒度分形分布对氡析出率的影响.结果表明,尾矿中氡的析出率呈现振荡性变化;在尾矿粒度分布分维值为2.3-2.8内,氡析出率随分维值的增大显著减小,至分维值为2.6时达到极小值,然后随分维值的增大略有增高.反冲作用与He-Rn团簇的形成和尾矿的非均匀性导致了氡析出的振荡变化.分维值增大,小颗粒尾矿含量增高,孔隙度减小,导致了氡析出率随分维值增大而减小.但是,随着分维值的增大,小颗粒增多,由反冲作用引起的氡释放进入孔隙的几率增大,又导致氡析出率随分维值增大而轻微增高.

The emanation of radon from the uranium tailings is a typical environment problem which is fully valued.The influence of fractal size distribution of tailings on radon emanation rate was experimentally studied.The results indicate that the radon emanation rate from uranium tailings behave oscillatory change.With the fractal dimension of 2.3-2.8,the radon emanation rate decreases evidently with the increasing of fractal dimension and reaches the minimum at the fractal dimension of 2.6,and then increases slowly with increasing of fractal dimension.Recoilling,He-Rn cluster forming and heterogeneity of uranium tailings lead to the oscillating change of radon emanation.With the increasing of fractal dimension of size distribution,the contents of small grain increase and the porosity decreases,which result in the decreasing of radon emanation rate with the increasing of fractal dimension.However,with the increasing of fractal dimension and the increasing of small grains,the probability that radon release to pore by recoilling increases,which cause that radon emanation rate increases slightly as the fractal dimension increases.