Wettability and reaction of copper slag with MgO, Al2O3, ZrO2, MgCr2O4, MgAl2O4, ZnAl2O4 and Mg2SnO4
Year: 2025
Type: article
Abstract: Using a copper slag containing 63.1 wt% Fe 2 O 3 , 23.0 % SiO 2 and 1.9–3.5 % each of PbO, CuO, Al 2 O 3 , CaO and MgO, corrosion resistance of > 97.2 % pure refractory aggregates sintered to 0.4–4.7 % apparent porosity were evaluated by hot stage microscope. At a fixed temperature of 1425°C, MgCr 2 O 4 displayed the greatest wetting angle (62°) and MgO had the largest relative height for the slag (91 % of starting 3 mm cube) demonstrating their superior corrosion resistance. MgO-MgCr 2 O 4 bricks are the prevalent refractory used in copper converters despite studies that warn that spent materials may contain carcinogenic hexavalent chromium that pose health hazards. MgO was found to be superior to Al 2 O 3 as base composition because of higher temperature of attainment of 90 % relative height of the slag (1425°C and 1412°C, respectively) and 30° contact angle (>1455°C and 1419°C). ZrO 2 and Mg 2 TiO 4 had the lowest temperatures for 90 % slag height (1405°C and 1396°C) and 30° contact angle (1402°C and 1406°C), revealing their poor corrosion resistance. Mg 2 SnO 4 formed a thick reaction layer of SnO 2 , Mg 2 SiO 4 and Fe 3 O 4 containing 5–5.1 at% each of Mg and Sn indicating severe corrosion. MgAl 2 O 4 and ZnAl 2 O 4 had 90 % slag height temperatures of 1417°C and 1413°C, and 30° contact angle temperatures of 1426°C and 1420°C. The most corrosion resistant chromium-free refractory for copper converter is expected to be MgO-MgAl 2 O 4 brick as both the phases exhibited delayed softening and spreading of slag. Upon reaction with MgAl 2 O 4 , low-melting fayalite-rich olivine in the starting slag was eliminated, magnetite solid solution remained along with a glass phase containing dissolved Al 2 O 3 , whereas MgO aggregate had Mg-rich glass and additional small amounts of high melting point compounds, Mg 2 SiO 4 and MgO-FeO solid solution at the reaction interface.
Institutions: AGH University of Krakow, Vesuvius (United States)
Language: English
Subfield: Mechanical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,900
OpenAlex ID: W4414105238