Optimization of a new animal glue binder system cured by CO2 for use in foundry

A new sand binder system cured by CO2 was prepared based on the animal bone glue. To overcome the disadvantages of animal glue such as agglomeration at room temperature, high energy consumption and low efficiency, an alkaline decomposition process was selected, and certain modifier was used to modify the performance of the animal glue binder. For the alkaline decomposition, NaOH was used as the catalyst with an addition of 4wt.% to the animal glue. A modifier was determined through the orthogonal experiment with a weight ratio of glycerin: glycol: dextrin: animal glue = 9:16:15:100, and the optimal modification reaction should be performed at 75 ℃ with a reaction time of 90 min. Ca(OH)2 was used as a promoter; the optimal CO2 gas flux blowing into the sand was 0.7 m3·h-1 for a duration of 60 s under the experimental conditions. Results show that an original strength above 0.7 MPa and a final strength about 4.2 MPa can be achieved, which could meet the requirement of rapid moulding and core-making for foundry. The new binder was characterized and analyzed by means of IR, and the modification and CO2-cured mechanisms of this animal glue binder were also discussed.