STABILIZATION OF UNIVERSAL SAND-CLAY MIXTURE PROPERTIES BY HYDRAULIC RECLAMATION

Abstract

Increasing the level of environmental friendliness and introducing waste-free technologies are necessary tasks of modern successful production. Casting in sand-clay molds, despite its long history, remains one of the most common and environmentally effective methods of casting manufacturing. Currently, about 70% of foundry waste consists of spent mixtures. Therefore, the mixture reclamation issue is relevant both from the point of view of increasing the environmental friendliness of production and from the point of view of reducing the cost of casting. The article is devoted to studying the influence of the reclamation process on the properties of a reversible sand-clay mixture for castings manufacturing from alloys of ferrous and non-ferrous metals in raw and dry casting molds. It was established that increasing of hydraulic reclamation cycle numbers leads to decrease of clay component amount to a level corresponding to quartz group sands (within 2,0%). Adding of fresh sand up to 20% to the regenerated mixture allows to increase the level of properties in the wet state. Increasing of reclamation cycle number cycles also has a positive effect on the physical, mechanical, and technological properties of mixtures with the addition of fresh sand and clay. However, one (first) reclamation cycle is enough to reduce the content of the clay component to the recommended limits. Increasing the mixing time of the regenerated mixture with added fresh sand and clay to 15–20 min has a positive effect on the properties of the mixture in the dry state, which is associated with the homogenization of its composition and uniform dispersion of clay over the particles of the added sand. Thus, the mixture after one regeneration cycle, for which a set mixing time with added fresh sand and clay is provided, is universal for wet and dry molds manufacturing for producing for ferrous and non-ferrous castings.