含APAM的高浓度全尾砂料浆内部结构演化特征

Internal structure evolution characteristics of high concentration unclassified tailings mortar containing APAM

矿山实际用于充填的全尾砂料浆往往低于设计浓度,且其中残留的絮凝剂对其内部结构影响甚大,全尾砂料浆的管道输送特征与之前大相径庭。为此,本文对添加和未添加阴离子聚丙烯酰胺(APAM)的全尾砂料浆开展了粒径测试、核磁共振(NMR)测试和扫描电镜(SEM)测试,综合采用计算机图像处理技术与分形理论,量化了全尾砂料浆在不同时间的结构演化特征。结果表明:1)APAM的添加增强了颗粒间的凝聚作用,更多游离的细颗粒在絮凝剂高分子长链的作用下参与形成絮团,料浆中颗粒的粒径增大;2)APAM促进了活跃的自由水逐渐转变为稳定形态的吸附水和絮团水,絮团水比自由水更加稳定而不易析出,有利于流体流动向层流发展,料浆稳定性增强;3)APAM高分子通过吸附架桥作用使颗粒排列更加紧密,随着静置时间的延长,料浆内部絮网结构不断发育,尤其未添加与添加APAM料浆的结构系数在0~20 min期间分别从0.947、0.960上升至0.984、0.998;4)APAM增大了料浆的屈服应力和塑性黏度,进而增大了沿程阻力,对于消耗部分多余的重力势能、减轻管道磨损破坏程度具有积极作用。因此,建议根据全尾砂料浆在管道内的输送时间,以添加絮凝剂后料浆屈服应力的稳定值计算沿程阻力损失。

The actual unclassified tailings mortar used for filling in mines is often lower than the design concentration,and the residual flocculant added in the thickening process has a great impact on the change of its internal structure.The pipeline transportation characteristics of unclassified tailings mortar are very different from those before.Therefore,the particle size test,nuclear magnetic resonance(NMR)test and scanning electron microscope(SEM)test were carried out for the unclassified tailings mortar with and without anionic polyacrylamide(APAM).The structural evolution characteristics of the unclassified tailings mortar at different time were quantified by using computer image processing technology and fractal theory.The results show that:1)the addition of APAM enhances the coagulation between particles,more free fine particles participate in the formation of flocs with the action of flocculant polymer long chain,and the particle size in the mortar increases;2)APAM promotes the gradual transformation of active free water into stable adsorbed water and floc water.Floc water is more stable than free water and is not easy to precipitate,which is conducive to the development of fluid flow to laminar flow and the enhancement of mortar stability;3)APAM polymer makes the particles arranged more closely through adsorption and bridging.With the increase of standing time,the floc network structure in the mortar continues to develop,especially during the period of 0-20 min,the structure coefficients of unapplied and added APAM mortar rise from 0.947 and 0.960 to 0.984 and 0.998 respectively;4)APAM increases the yield stress and plastic viscosity of the mortar,and then increases the resistance along the way,which plays a positive role in consuming some excess gravity potential energy and reducing the degree of pipeline wear and damage.Therefore,it is suggested to calculate the resistance loss along the way according to the transportation time of the unclassified tailings mortar in the pipeline and the stable value of the yield stress of the mortar after adding flocculant.