风化壳淋积型稀土矿原地浸出工艺是开采战略性中-重稀土资源的重要技术手段.注液过程中,矿体所含蒙脱土等黏土矿物水化膨胀会诱发山体滑坡,造成资源浪费.为此,选用聚二甲基二烯丙基氯化铵(PDDA)为抑膨剂,研究其对蒙脱土和稀土矿物颗粒的抑膨性能及作用机理.线性膨胀试验结果表明,质量浓度 0.5%的PDDA溶液即可对蒙脱土和稀土矿物颗粒产生良好的抑膨效果.激光粒度、SEM和沉降分析显示,PDDA可使细小矿物颗粒絮凝团聚,减少矿物表面孔隙,提高沉降效率,防止其水化分散.红外光谱、Zeta电位和XRD分析证明,PDDA有机阳离子基团可吸附于矿物颗粒表面,中和黏土矿物表面负电荷,抑制其晶层间距水化扩张.此外,常用稀土浸取剂硫酸铵对PDDA的抑膨作用无明显干扰.本研究可为稀土原地浸出过程中矿体抑膨剂的选择和应用提供参考.
The in-situ leaching process for weathered crust elution-deposited rare earth ores(WCE-DREO)is an impor-tant technology for mining medium-heavy rare earths.During the leachate injection process,the hydration swelling of clay min-erals such as montmorillonite in the ore body could induce landslides and waste resources.In this work,poly-(dimethyl diallyl ammonium chloride)(PDDA)was selected as a swelling inhibitor.Its swelling inhibition performance and mechanism on the mineral particles of montmorillonite and rare earth were investigated.Linear swelling experiments indicated that 0.5%PDDA solution is sufficient to produce good swelling inhibition effect for the mineral particles of montmorillonite and rare earth.Laser particle size,SEM and sedimentation analyses showed that PDDA could agglomerate fine mineral particles,reduce the pore space on the mineral surface,increase the settling efficiency and prevent its hydrological dispersion.FTIR,Zeta potential and XRD analyses demonstrated that the organic cationic groups of PDDA could be adsorbed on the surface of mineral particles to neutralize the negative surface charge of clay minerals,and inhibit the hydrological expansion of their crystal interlayer spacing.In addition,ammonium sulfate solution which commonly used as the rare earth leaching agent,did not significantly interfere with the swelling inhibition effect of PDDA.The result of this study could provide a reference for the selection and application of swelling inhibitors in the in-situ leaching process of rare earth mines.