Dual-strength mechanisms in low-carbon cold-bound pellets: binder synergy and sinter fines recycling for sustainable ironmaking

In pursuit of more efficient low-carbon ironmaking, fulfilling the requirements of blast furnace materials, four types of low-carbon cold-bound pellets were prepared from blended iron ore, which were dually strengthened through sintered return fines and binder. The strengthening mechanism of low-carbon cold-bound pellets was discussed based on the analysis of the characterization results including optical microscopy, scanning electron microscopy-energy dispersive spectroscopy, X-ray diffraction and Fourier transform infrared spectroscopy and the reduction performance detection results. The results demonstrate that, when subjected to external forces, the interlocking of returned fines with blended iron ores leads to the formation of a load-bearing skeleton. During the drying process, the binder is dehydrated and condensed to yield a gel network structure, with which the bonding effect is imposed. In contrast to the organic binder PR, the inorganic binder SS ensures a stabler thermal structure and reduction performance for the cold-bound pellets. The comparison of energy consumption and carbon emissions was estimated before and after introducing cold-bound pellets in the process, and it was ascertained that low-carbon cold-bound pellets are able to foster the low-carbon sustainable ironmaking.