Hardening of foundry sand moulds or cores in boxes - where continuous recirculation of catalyst gas mixt. via compressor greatly reduces consumption of catalyst

摘要

An exact amt. of a catalyst in the gaseous state is driven through the core- or mould-box via a closed air circuit so the gas is recirculated together with the air through the sand. The pref. plant includes a core box provided with gas inlet and outlet pipes connected in a closed circuit which includes a compressor driving the gas through a sand core; and the closed circuit includes an inlet valve for the injection of the catalyst. When using N2 contg. 16 vol.% of dimethyl-ethylamine as a catalyst, only about 0.002% the amine is required w.r.t. the wt. of sand; but conventional mass prodn. foundry equipment uses up to 180 times this amt. Amine consumption is reduced to near the value of 0.002%.