Method for preparing lithium hydroxide monohydrate by using salt lake brine as raw material

The invention discloses a method for preparing lithium hydroxide monohydrate by using salt lake brine as a raw material. The method comprises the following steps: providing lithium-containing brine, wherein the lithium-containing brine is obtained by carrying out potassium extraction and refining on salt lake old brine; carrying out evaporation treatment on the lithium-containing brine, at least reducing the sodium/lithium ratio in the lithium-containing brine to 0.1 or below, and then carrying out separation treatment to obtain a lithium-rich solution; and under a stirring condition, adding an alkali solution into the lithium-rich solution for reaction crystallization, and separating to obtain lithium hydroxide monohydrate and a mother solution. The preparation method provided by the invention can solve the problem of a technology for producing lithium hydroxide by utilizing salt lake brine resources, and meanwhile, the method is low in energy consumption, low in investment, simple, feasible and convenient t