Internal re-use of uncured core sand

Core production generates sand residues in the form of broken cores, cones with small mistakes and excess sand from the core-making machines. The excess sand can be hardened in a specific unit. Subsequently the various unused core sand flows are fed to a breaking unit. The resulting sand may be mixed with new sand for the production of new cores. 

Internal re-circulation of 5 - 10 % of the core sand, which otherwise would be disposed of. 

This technique applies for pol5mrethane (cold-box) and fliran resin-bonded sands. Other binders do not allow this technique. 

The implementation of the technique necessitates changes in the process control. The optimum ratio of re-circulated and new sand will need to be determined. Additionally changes in binder addition or composition may be needed. 

The technique requires an investment cost of EUR 250000 - 500000 for the eombined treatment and breaking unit. Operational eosts are about EUR 12/t. These eosts are balanced by a reduction in disposal costs and purchasing costs for new sand. 

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