Processes and systems for preparing lithium hydroxide

A process for preparing lithium hydroxide, said process comprising:

• submitting, in a first electrochemical cell that comprises a two-compartment membrane cell, an aqueous composition comprising lithium sulfate and/or lithium bisulfate to a first electromembrane process that comprises a two-compartment membrane process for conversion of said lithium sulfate and/or lithium bisulfate to lithium hydroxide, and obtaining a first lithium-reduced aqueous stream and a first lithium hydroxide-enriched aqueous stream;
• monitoring conversion of said lithium sulfate and/or lithium bisulfate into lithium hydroxide such that when consumption of said lithium sulfate and/or lithium bisulfate reaches 30 to 50 weight %, conveying said first lithium-reduced aqueous stream from an anolyte compartment of said first electrochemical cell to a central compartment of a second electrochemical cell that comprises a three-compartment membrane cell;
• and
• submitting said first lithium-reduced aqueous stream to a second electromembrane process that comprises a three-compartment membrane process to prepare at least a further portion of lithium hydroxide and obtaining a second lithium-reduced aqueous stream, sulfuric acid and a second lithium-hydroxide enriched aqueous stream.