Dual effect of MgO on softing–melting performance of high gangue sinter: changes of slag viscosity and phase composition

In this paper, through softening–melting test of sinter with high MgO content produced by iron and steel enterprises, the double influence of high MgO concentration on soft melting performance of sinter was researched. The experimental results show that in the sinter melting process, on the one hand, the slag viscosity will gradually decrease from 0.107 to 0.095 Pa·S at 1540°C with the increase in MgO content in the sinter. On the other hand, with the increase in MgO content, the content of solid oxide in sinter slag at 1540°C increases from 2.41% to 15.31%, the separation of slag and iron at high temperature also makes a large number of MgO elements precipitate out in solid phase, which hinders the flow performance of slag. In addition, the influence amplitude of MgO content on the melting performance of sinter mainly depends on gangue content in sinter.