Analysis and Chromium Recovery from Ferrochrome Waste (Stockpiled Refined Ferrochrome Slags)

Abstract

This study investigates the effectiveness of various beneficiation methods for recovering chromium from refined ferrochrome slag. Dry magnetic separation at different field intensities (0.45 T and 0.8 T) showed that selective extraction of metallic chromium (Crmet) is more efficient at 0.45 T, achieving a recovery rate of up to 90.05%. Pneumatic separation using SEPAIR technology demonstrated promising results, especially for wide particle size fractions (0–20 mm), where chromium recovery reached 40.32% due to density differences between slag particles and metallic inclusions. Enrichment on a shaking table proved to be the most selective method, producing a concentrate with 29.9% Cr and 90.7% recovery, although the yield was low (3.8%). SEM-EDX and SEM-BSE analyses confirmed the heterogeneous phase composition of slag grains, revealing chromium–iron alloys embedded in oxide matrices. Based on laboratory experiments and material characterization, it is concluded that magnetic separation can be used for preliminary concentration, pneumatic classification is effective for processing bulk slag with economic potential, and gravity concentration on shaking tables is suitable for producing high-grade concentrates. The resulting tailings, low in chromium, are suitable for reuse in the production of building materials after carbonation treatment.