Abrasion resistance and hardness of Cr-free zinc and iron co-doped spinel and magnesia-spinel refractory matrices for copper smelting

Abrasion resistance is one of the least studied properties of refractories despite its significant contribution to wear mechanisms. This work investigated the abrasion resistance and Vickers hardness of ZnO+Fe 2 O 3 (3:1 by weight) doped alumina-rich spinel and magnesia-spinel that contained multicomponent (Mg,Zn)[Al,Fe] 2 O 4 spinel as a major and minor phase, respectively. Sintered Al 2 O 3 , MgO-stabilized ZrO 2 and MgO were used as standard reference refractory raw material aggregates for comparison. Stationary samples at room temperature were rubbed against a vertically rotating rubber lined wheel on which SiC particles were fed. This abrasion test revealed that (Mg,Zn)[Al,Fe] 2 O 4 spinel occurring as individual grains along with sub-micron precipitates within magnesia grains increase abrasion resistance as compared to MgO. Microstructure of abraded surfaces identified wear mechanisms like microcracking, grain pullout formed craters, abrasion grooves and scraped patches. 3% doped magnesia-spinel and 34% doped alumina-rich spinel were found to be promising wear resistant matrix compositions to make environment-friendly chromium-free refractories for the copper industry. • New zero-Cr multicomponent spinels (Mg,Zn)(Al,Fe) 2 O 4 and magnesia-multicomponents spinel aggregates were synthesized • Materials were based on commercial Al-rich spinel AR78 doped with ZnO+Fe 2 O 3 and DBM magnesia • Hardness and abrasion resistace of new aggregates was explored • Al 2 O 3 , magnesia-stab. ZrO 2 , MgO were used as standards • Precipitation strengthening was found in MgO-spinel materials