A Scalable Process for the Production of Calcium Formate from Lime Mud

The utilization of industrial side streams for generating value has always been of interest, but in today’s society, with a high focus on the circular economy, it is becoming increasingly important. Lime mud (whose major component is calcium carbonate, CaCO₃) is a low-value by-product of the pulp and paper industry that is generated in considerable amounts during the causticizing process. Designing routes for lime mud valorization would present new opportunities for integrated biorefineries possessing an effective solid waste reduction. In the present study, a scalable process for the production of high-value calcium formate (Ca(HCO₂)₂) from CaCO₃ is developed. An alternative method is examined, where CO₂ and H₂ are used to react with CaCO₃ to be converted into Ca(HCO₂)₂ under mild operating conditions. The process uses a heterogeneous catalyst to react with the components in the system consisting of two solids, one liquid, and two gaseous compounds. The process development reported spans lime mud conditioning, catalyst development, process design and scale-up, including a preliminary techno-economic assessment.