改性黄麻纤维联合微生物胶结铀尾砂的抗渗性能试验研究  

Experiment on the impermeability of uranium tailings treated by microbial induced calcium carbonate precipitation combined with modified jute fiber

作　　者：贺桂成 唐孟媛 李咏梅 李春光 张志军 伍玲玲 HE Gui-cheng;TANG Meng-yuan;LI Yong-mei;LI Chun-guang;ZHANG Zhi-jun;WU Ling-ling(School of Resource Environment and Safety Engineering,University of South China,Hengyang,Hunan 421001,China)

机构地区：[1]南华大学资源环境与安全工程学院,湖南衡阳421001

出　　处：《岩土力学》2023年第12期3459-3470,共12页Rock and Soil Mechanics

基　　金：国家重点研发计划项目(No.2021YFC2902104);国家自然科学基金(No.52274127,No.51974163);湖南省教育厅科学研究优秀青年项目(No.20B494,No.22B0430)。

摘　　要：利用改性黄麻纤维联合微生物诱导碳酸钙沉淀(microbial induced calcium carbonate precipitation,MICP)技术能有效胶结充填铀尾砂中的孔隙,提高堆浸铀尾砂的抗渗性能。通过研究铀尾砂的颗粒级配、胶结液浓度以及改性黄麻纤维的长度、质量含量和水热处理时间等因素对改性纤维联合微生物胶结铀尾砂的渗透系数的影响,获取最优的胶结参数;采用扫描电镜和X射线衍射仪等测试设备,表征了改性黄麻纤维联合MICP胶结铀尾砂形成的碳酸钙晶体的结构类型,分析其抗渗机制。研究结果表明:经水热处理后的纤维表面粗糙度增大,为微生物提供更多的附着场所,促进了微生物在铀尾砂中的生长、繁殖、迁移和固定,增加了碳酸钙晶体的生成量,提高了碳酸钙沉淀的均匀性,降低了铀尾砂的渗透系数;在颗粒级配编号为A3的铀尾砂中,改性纤维联合MICP胶结后的铀尾砂的渗透系数大幅降低,且纤维长度为20 mm、纤维质量含量为0.5%、纤维水热处理时间为2 h、胶结液浓度为2 mol/L时,经过11轮注浆后铀尾砂的渗透系数降低了99%,此时的参数是最优的;改性纤维联合MICP胶结铀尾砂生成的碳酸钙晶体在衍射角2θ分别为23°、29.4°、36°、39.3°等多个位置出现方解石特征峰,此时的晶体结构为方解石。Microbial induced calcium carbonate precipitation(MICP)technology combined with modified jute fiber can effectively cement the uranium tailings and fill the pore between the particles,thus,improve the impermeability of uranium tailings.In this study,the effects of some parameters,such as particle gradation,concentration of cementing solution,as well as the length,mass content and hydrothermal treatment time of modified jute fiber,on the impermeability of uranium tailings cemented by microbe in coordination with modified fiber were studied,and the best values of these parameters were determined.Then,the structure type of calcium carbonate crystal produced by MICP and modified fiber was analyzed using the scanning electron microscope(SEM)and X-ray diffraction(XRD),in order to analyze the impermeability mechanism.The results showed that the modified fibers provided more spots for bacterial adhesion,due to the increased surface roughness by hydrothermal treatment.This promoted the growth,reproduction,migration and fixation of microorganisms in uranium tailings,increased the uniformity of calcium carbonate precipitation,and decreased the permeability coefficient of uranium tailings.In the case of gradation number A3,the permeability coefficient of the cemented tailings decreased sharply.When the fiber length,fiber mass content,hydrothermal treatment time of fiber and the cementing solution concentration were 20 mm,0.5%,2 h and 2 mol/L,respectively,the permeability coefficient of uranium tailings decreased by 99%after 11 rounds of bio-grouting,indicating these values are optimal.The calcium carbonate crystal,formed in the cemented uranium tailings by the modified fiber combined with MICP,presented calcite characteristic peaks at diffraction angles 2θof 23º,29.4º,36º,39.3º,which demonstrated that the crystal is mainly calcite.

关 键 词：铀尾砂 改性黄麻纤维 微生物诱导碳酸钙沉淀 渗透系数 抗渗性能 

分 类 号：O319.56[理学—一般力学与力学基础] TU451[理学—力学]