Destruction Mechanism of Magnesia-chromium Bricks Used in Copper Smelting Furnaces

Magnesia-chromium refractory material is a kind of refractory material mainly composed of magnesia and supplemented by chromite.

Refractory bricks commonly used in the copper smelting industry include: ordinary silicate bonded magnesia chromium bricks, direct bonded magnesia chromium bricks, rebonded magnesia chromium bricks, semi-rebonded magnesia chromium bricks, co-sintered magnesia chromium bricks, and fused cast magnesium chrome bricks. Magnesia-chromium refractory bricks are subject to high temperature and chemical erosion for a long time in the daily operation of high-temperature kilns in the copper smelting industry. The main damage mechanisms are as follows:

01 Copper slag and copper melt can gradually penetrate into the interior along the pores of magnesia-chrome bricks. The slag and copper melt entering the interior fill the pores and cracks, causing thermal breakdown of the furnace lining and expansion and peeling.

02 The viscosity of iron-silicon slag is relatively low. The iron-silicon slag that penetrates into the magnesia-chromium brick forms a continuous network and forms a metamorphic layer. The metamorphic layer causes different thermal expansions of the bricks, causing cracks to form in the bricks and gradually expand, causing the bricks to peel off. Moreover, when SO2 migrates in the brick body, an oxidation reaction occurs to generate SO3, and it combines with alkaline oxides to form low-melting-point alkaline metal salts, thereby aggravating the penetration and erosion of slag.

03 Regarding the destruction of sulfur element, at 1500°C, the sulfur content in the slag is relatively high. During the migration process of SO2 magnesia chromium bricks, there is a process in which sulfate is first generated and then decomposed. This process will cause the expansion of pores in the brick body and the loosening of the structure, and deepen the erosion of converter copper slag on magnesia-chromium refractory materials. At 1300°C, the corrosion resistance of directly bonded magnesia chromium bricks is better than that of fused semi-rebonded magnesia chromium bricks. At 1500°C, the corrosion resistance of fused semi-rebonded magnesia chromium bricks is better than that of directly bonded magnesia chromium bricks.

04 Flue gas erosion and mechanical wear will also accelerate the erosion of magnesia-chromium bricks.