Anti-swelling mechanism of DMDACC on weathered crust elution-deposited rare earth ore

In order to inhibit the swelling of the clay minerals in the in-situ leaching process of weathered crust elution-deposited rare earth ores (WCE-DREO), diallyl dimethyl ammonium chloride (DMDACC) was introduced as an anti-swelling agent and combined with (NH 4 ) 2 SO 4 as a novel composite leaching agent. It can be found that the novel composite leaching agent exhibits a good anti-swelling performance and leaching capacity of rare earth, and has great potential on the actual exploitation of WCE-DREO. The anti-swelling mechanism of DMDACC was studied by characterization analysis. The results show that DMDACC with positive charges can adsorb on the clay particles by the electrostatic attraction and hydrogen bonds, and neutralize the negative charge of the clay particles. The double electrical layers are suppressed and the repulsion force between clay sheets decrease. It causes the clay particles prone to aggregate. Moreover, DMDACC can enter the interlayer and expel out the water molecules in interlayer. The interlayer spacing is decreased and the hydration swelling of the clay particles is weakened. It can provide a theoretical basis for the development of novel anti-swelling agents. DMDACC can neutralize the negative charge, suppress the double electrical layers and promote the aggregation. DMDACC also can decrease interlayer spacing and weak the hydration swelling. • DMDACC was used as an anti-swelling agent to inhibit the swelling of clay minerals in the in-situ leaching process of WCE-DREO. • DMDACC combined with (NH 4 ) 2 SO 4 exhibited a good anti-swelling performance and leaching capacity of rare earth. • DMDACC could neutralize the negative charge of the clay particles, suppress the double electrical layers and promote the aggregation. • DMDACC could decrease interlayer spacing by expelling out the water molecules.