不同细粒含量尾矿沉降规律与其沉积体孔隙分布特征研究

Study on sedimentation laws of tailings with different fine particle contents and pore distribution characteristics of its sedimentary body

为了研究细粒尾矿沉降规律及其沉积体孔隙特征,开展不同细粒含量尾矿一维沉降柱试验,基于核磁共振获取不同细粒含量尾矿沉积体孔隙分布。研究结果表明:细粒含量较低时,尾矿浆液的沉降方式为粗粒自由沉降+细粒絮团沉降的混合方式;细粒含量较大时,尾矿浆液的沉降方式为粗粒自由沉降+细粒絮网沉降的混合方式;沉积体内部束缚水存在吸附水和絮团水2种形式,为导致沉积体赋存结构差异的主因;尾矿沉积体的孔隙孔径分布具有双峰特征,主峰(小孔径孔隙)分布在0.2~2μm,次峰(大孔径孔隙)分布在5~18μm,整体以小孔径孔隙为主,宏观上表现为不利于尾矿坝体的渗透。研究结果可为尾矿坝坝体结构的揭示和坝体安全评价提供参考。

In order to study the sedimentation laws of fine-grained tailings and the pore characteristics of sedimentary bodies,the one-dimensional sedimentation column test of tailings with different fine particle contents was carried out,and the pore distribution of tailing sedimentary body with different fine particle contents was obtained by using the nuclear magnetic resonance(NMR).The results show that when the fine particle content is low,the sedimentation pattern of tailings slurry is a mixed pattern of coarse particle free sedimentation and fine particle floc sedimentation.When the fine particle content is large,the sedimentation pattern of tailings slurry is a mixed pattern of coarse particle free sedimentation and fine particle flocculent net sedimentation.The presence of both adsorbed and flocculated water within the sedimentation body is the main cause of the differences in deposit structure of sedimentation body.The pore size distribution of the tailings sedimentation body has bimodal characteristics,the main peak(small pore size pores)is distributed in 0.2~2μm,and the secondary peak(large pore size pores)is distributed in 5~18μm,with small pore size pores dominating overall,which is unfavorable to the permeability of the tailings dam on the macro level.The results can provide a reference for revealing the structure of tailings dams and evaluating the safety of dams.