Calcium oxalate - a source of "hickey" problems - A literature review on oxalate formation, analysis and scale control

Calcium oxalate is one of the most problematic scale salts occurring in pulp and paper production processes. Calcium oxalate scaling in a paper machine system often leads to disturbances in the process, production losses due to downtime needed for cleaning, as well as impaired paper quality. This literature review gives a summary of current Knowledge and recent research on oxalic acid and calcium oxalate formation especially in mechanical pulping. Methods for oxalate analysis, as well as possible ways to control and monitor the scaling in the process, are also discussed. Finally, possibilities to utilize oxalic acid and calcium oxalate in the process are briefly reviewed.