A novel recycling and reuse method of iron scraps from machining process

Abstract

The rational recycling and reusing of a large number of iron scraps from machining has become an urgent problem. Whereas, it is inappropriate that iron scraps are directly used as charge materials for the melted reusing because the iron scraps with high specific surface area and fine particles may lead to oxidation of Fe and loss of alloying elements. In order to better utilize iron scraps, an effective method was developed in this work. First of all, the dispersed iron scraps have been compressed into iron scrap cakes by use of an auto hydraulic metal block machine. The fabricating process and characteristics of iron scrap cakes were described. Green density and compressive strength of iron scraps block were examined. Subsequently, a simulation experiment for iron cakes to be heated in a furnace was carried out and chemical composition difference between the outside surface and the inner surface of iron cake was analyzed by using scanning electron microscope equipped with energy dispersive spectroscopy (SEM -EDS). Meanwhile, manufactured iron scrap cakes replaced pig iron were added into an intermediate frequency furnace, melted into liquid iron and cast into sound castings. Effect of iron scrap cakes on microstructure and mechanical properties of ductile iron and grey iron casting was examined. Finally, iron scrap cakes were adapted to mass production in the foundry plant. The result shows that iron scrap cakes are characterized by higher green density (5.6 t/m3) and compressive strength (more than 50 MPa), higher material yield rate (more than 90%), lower material cost and environmental pollution, less energy consumption and less flue gas and other emissions than dispersed iron scraps. As a result, the new method is environmentally friendly, bringing about remarkable economic and social benefits for the enterprise.