GB1322864A - Process and apparatus for the regeneration of foundry sand - Google Patents

Abstract

1322864 Regeneration of foundry sand SOC D'APPLICATION DE PRODUITS INDUSTRIELS ET CHIMIQUES SARL 29 Nov 1971 [30 Nov 1970] 55181/71 Heading B2H [Also in Division B3] A process for the regeneration of foundry sand comprises breaking the moulds, crushing the hot lumps of sand obtained therefrom, cooling the crushed sand to ambient temperature, separating the grains of sand from their coating of a binding agent by projecting them against the wall of a chamber to cause the matrix of binding agent to burst, submitting the sand thus obtained to granulometric selection by at least two screens, and removing dust from the sand in at least one stage of the process, where the dust is formed. After the mould has been broken up using a stationary, vibrating or impact type grid 1, the sand is gushed in the unit 2. and passed through a sand cooling unit 3 which is preferably of the fluid bed type. It is then carried to the top of a device 6 by a conveyor 4 provided with a separator for metalic particles, and an elevator 5. In the device 6, Fig. 4, the sand is subjected to horizontal jets of air issuing from pipes 9 which force the sand against baffles 8. A fine spray of water may be introduced into the device 6 from an atomiser 15 for cooling purposes. Dust is withdrawn through an outlet 11 whilst the sand passes through an outlet 12 to a screening apparatus 17 having between two and eight screens arranged above one another. From here the coarse fraction is either collected in a hopper 25 or conveyed to a secondary crusher 22 and reintroduced into the bottom of the elevator 5. An intermediate fraction is collected in a hopper 19 and reused in the manufacture of moulds, and a very fine fraction is drawn off into a chamber 26. The dust produced in earlier stages of the process is also conveyed to the chamber 26, where it is removed in filter sacks 26a or in a wet separation apparatus.