Experimental Study On Resource Utilization Of Lithium Extraction Tailings From Spodumene

With the vigorous development of new energy,the demand for lithium batteries is increasing rapidly,and the prospects for the lithium battery industry are very broad.As a key raw material for the development of new energy,the processing technology of lithium salt is mainly the sulfuric acid roasting method,but this technology will produce a large amount of tailings,cause waste of resources and pollute the environment,which need to be solved urgently.In this study,with the hydrothermal alkaline process and using the tailings of lithium extraction from spodumene as the raw material,the nano-kaolinite,hydrated calcium silicate and xonotlite products are successfully prepared to realize the high-value utilization of the solid waste resources.The main research results of this article are listed as below.（1）The decomposition process of Washed-lithium slag-Na OH-H₂O system was investigated.The effects of reaction temperature,reaction time and Na OH/HNO₃concentration on the synthesis of hydroxycancrinite and nano-kaolinite were explored by a two-step hydrothermal method,and the reaction mechanism was discussed in detail.The lithium slag was completely decomposed into sodalite in 6 mol/kg Na OH solution at 220℃,and then transformed into hydroxycancrinite.Nano-kaolinite was successfully prepared by the reaction of 0.65 mol/kg HNO₃solution with the intermediate product of hydroxycancrinite at 260℃for 24 h.（2）Using the Washed-lithium slag desilication filtrate as the siliceous raw material and CaO as the calcium raw material,the effects of reaction temperature,reaction time,liquid-solid ratio and stirring speed on the hydrated calcium silicate powder were investigated by a one-step hydrothermal method.Under the conditions of 100℃,liquid-solid ratio of 10,reaction time of 1h,and stirring speed of 300 r/min,a calcium silicate hydrate powder with D90<10μm was synthesized.（3）Using the Washed-lithium slag desilication filtrate as the siliceous raw material and CaO as the calcium raw material,the influence of reaction temperature,reaction time,liquid-solid ratio and aging time on the synthesis of xonotlite was investigated through a two-step hydrothermal method.The reaction mechanism is discussed.The xonotlite with a hollow secondary structure and whisker aspect ratio of 40 was successfully synthesized under the conditions of 260℃,liquid-solid ratio of 20,reaction time of 24 h,and aging time of 12 h.Herein,the synthesis of nano-kaolinite by-product calcium silicate hydrate or xonotlite from lithium slag has important practical value for the resource utilization of industrial spodumene lithium extraction tailings.