Ultrasound-assisted leaching of rare earths from the weathered crust elution-deposited ore using magnesium sulfate without ammonia-nitrogen pollution.

The in situ leaching process of China's unique ion-adsorption rare earth ores has caused severe environmental damages due to the use of (NH)SO solution. This study reports that magnesium sulfate (MgSO) as a leaching agent would replace (NH)SO by ultrasonically assisted leaching to deal with the ammonia-nitrogen pollution problem and enhance leaching process. At leaching conditions of 3wt% MgSO concentration, 3:1L/S ratio and 30min, the total rare earth leaching efficiency reaches 75.