Experimental Study on Stainless Steel Dust by Reduction and Enrichment for Preparation Raw Material of Powder Metallurgy

Abstract

During the production of stainless steel, dust of size less than 50 μm is produced. It has been estimated that the production of one ton stainless steel can produce l8–33 kg dust, which contains a large amount of Fe, Cr, Ni and other valuable metals. In this study, according to the composition requirements of iron-based powder metallurgy friction materials on raw materials, the physicochemical properties of 400 series stainless steel dust were analyzed. The dust was magnetically selected, and the low-medium reduction magnetic separation was adopted, which was explored as a new process for the preparation of powder metallurgy friction material. Considering the magnetic material yield, TFe grade and decalcification effect, the suitable magnetic field strength ranges from 60 to 90 mT and the reduction temperature is from 800 to 900 °C. The main phases of the primary magnetic material after reduction include Fe, FeCr2O4, chromium carbides (Cr3C2 and Cr7C3), MgO and graphite (C), indicating that Fe3O4 is reduced to elemental Fe and FeCr2O4 and MgO are still present in material. Only a small part of the material reduces to chromium carbide at medium and low temperature (800–900 °C).