Towards electrifying cement production by electrochemically-enhanced dissolution of CaCO3 during water electrolysis under a pH-gradient

The cement industry, which accounts for 7-8% of worldwide CO2 emissions, is essential to decarbonize but challenging especially due to its high process emissions, high temperature heat requirements and low maturity of decarbonization solutions. A new electrochemical path to produce calcium hydroxide, a precursor of cement, has been proposed recently. This technology is based on a new design of a water electrolyser working in tri-phase environment. It has the potential to electrify cement production while at the same time producing valuable gases, but is still at a very early stage of development (TRL-3). In this paper, lab-scale experiments in a 200mL cell were performed to have a better understanding of the electrochemical system. The development of a pH gradient between the anode and the cathode has been quantified for different electric charges applied. Due to acidification of the anode side, the dissolution of calcium carbonate is enhanced. A solubility ten times higher than at neutral pH has been observed. At the same time, the migration of Ca2+ and OH- ions to respectively the cathodic and anodic side has been demonstrated as well, thereby opening the way for an electrochemically-enhanced Ca(OH)2 precipitation.