Granulated material, and production method of same, as additive for improving properties of foundry molding sands

摘要

The invention refers to a granulated material for preparation of foundry molding sand, to be added to them to improve their composition, reduce pollution and handling problems, which consists of a refractory framework in the form of granules the size of which ranges from 0.1 to 0.4 mm and an external coating on said refractory framework which in turn consists of a fit material for providing lustrous carbon. The refractory framework is formed by a zircon sand, chamotte, chromite, olivine, sil- limenite, mullite or mixtures thereof, with a free silice content not greater than 3%. The invention also relates to a hot-process and a cold-process for production of said granulated material.