Low-grade clay type lithium resource comprehensive utilization process

The invention relates to the technical field of lithium recovery, in particular to a low-grade clay type lithium resource comprehensive utilization process which comprises the following steps: S1, grinding raw ore into fine particles, and sequentially performing constant-temperature roasting, constant-temperature acid leaching, filtering and washing to obtain leached residues and a leached solution; s2, adding ammonium sulfate into the leaching solution, and filtering to obtain an aluminum ammonium sulfate crude product and crystallization tail liquid; s3, after new acid and water are supplemented into the crystallization tail liquid, the crystallization tail liquid is used for constant-temperature acid leaching again; s4, repeating the steps S1 to S3 for multiple times to obtain lithium-rich crystal tail liquid; s5, concentrating the lithium-rich crystallization tail liquid, adding NaOH to remove impurities, and then carrying out evaporation concentration, cooling, crystallization and filtration to obtain so