Abstract:Calcined briquetting was prepared by adding MgO to hematite. Mechanism of effect of MgO addition on composition and compressive strength of roasting compaction was investigated with combination of ore phase microscopy, scanning electron microscopy, compressive strength testing, and FactSage thermodynamic calculations. The results show that porosity drops obviously with increase of MgO addition. Magnetite content in roasting briquetting rises and hematite content drops with increase of MgO content. The interwoven structure of hematite and magnetite has good comprehensive micro-mechanical properties. In oxidative roasting process, magnetite content should be raised appropriately to increase compressive strength of briquetting. When addition amount of MgO is 2% and 4%, magnetite content in calcined briquetting is 18.97% and 24.16% respectively, and compressive strength of every briquetting is 1.924 kN and 1.993 kN respectively without binder addition.