Method for producing lithium hydroxide by dissolving spodumene out of pipeline reactor

The invention provides a method for producing lithium hydroxide by dissolving spodumene out of a pipeline reactor. The method comprises the following steps: carrying out size mixing on water and beta spodumene powder, sodium hydroxide and lime which are obtained by transforming a calcined crystal, delivering into the pipeline reactor by using a pump, mixing by utilizing the flow of slurry in a pipeline, and reacting at a certain temperature and pressure; after the reacted slurry flows out of the pipeline reactor, carrying out solid-liquid separation; and carrying out concentration, impurity removal, crystallization and mother solution circulation on filter liquor to obtain a lithium hydroxide product. The method provided by the invention is simple in lithium hydroxide production process, small in investment, low in production energy consumption and high in lithium extraction rate without sodium sulphate frozen precipitation or sulfuric acid transformation.