Comprehensive utilization of waste residue from lithium extraction process of spodumene

•High value products were successfully synthesized from waste residue.•Lithium slag is fully utilized and no waste is produced.•The whole process meets the requirements of environmental protection. In this work, the comprehensive utilization of spodumene waste residue - lithium slag is achieved. An experimental scheme of hydrothermal preparation of nano-kaolinite and xonotlite from it is proposed. The W-lithium slag is completely decomposed into sodalite and then transformed into hydroxycancrinite in 6 mol/kg NaOH solution at 220 ℃. As an intermediate product, hydroxycancrinite was reacted with 0.65 mol/kg HNO3 solution at 260 ℃ for 24 h to prepare nano-kaolinite successfully. The desiliconization filtrate produced by the reaction of W-lithium slag and NaOH solution was used as raw material, mixed with CaO and reacted at 260 ℃ for 12 h after aging for 12 h, then xonotlite was successfully prepared. This work demonstrates great potential on green recycling of spodumene waste residue from lithium extraction process and introduce a new economical processing technique for the slag as well.