Clean production technology of Baiyun Obo rare earth concentrate decomposed by Al(OH)3-NaOH

•A new clean extraction method of mixed rare earth concentrate is proposed.•The transformation mechanism and migration rule of Al3+ and F− were revealed.•The new way of transformation of rare earth alkaline wastewater was confirmed.•The internal circulation system of CO32− was established.•This reduces CO2 emissions at the source.