The hydrogenation and pyrolysis of this process are both continuous operations. Firstly, industrial grade lithium carbonate is mixed with pure water and returned mother liquor in a certain proportion and transported to a continuous hydrogenation tower through a pump. Carbon dioxide gas is introduced into the hydrogenation tower, and a lithium bicarbonate solution is obtained through hydrogenation at a certain pressure and temperature. After hydrogenation, the completed liquid is filtered and precisely filtered by a filter press, and then enters the resin impurity removal system for impurity removal. After impurity removal, the liquid is transported by a pump to the continuous pyrolysis tower for pyrolysis. The pyrolysis finished liquid is then centrifuged and separated by a centrifuge. The wet materials separated by centrifugation are dried, screened, iron removed, crushed, and packaged to obtain high-purity lithium carbonate products. Part of the pyrolysis mother liquor is returned to the mixing tank for mixing, while some is extracted for further processing. The carbon dioxide generated by pyrolysis in the pyrolysis system enters the carbon dioxide recovery device for recovery, and the recovered carbon dioxide is then returned to the hydrogenation system for reuse.