Low-carbon preparation of blast furnace burden from iron ore concentrate through cold-bonding: briquetting–curing characteristics and high-temperature strength evolution mechanism

Under the “dual-carbon” targets, low-carbon preparation of blast furnace (BF) burden is of great importance. Cold-bonded briquetting avoids high-temperature processing and can reduce CO 2 emissions. This study examined the briquetting–curing behavior of iron ore concentrate and clarified the high-temperature strength evolution of cold-bonded briquettes (CBBs) and the binder action mechanism. The results showed that binder type, briquetting pressure, briquetting moisture, and curing schedule affected CBB performance. With 2.4 wt.% composite binder and selected conditions (1.0 t/mm line pressure, 4.5 wt.% moisture, curing at 100 °C for 40 min), the wet briquettes achieved a drop number of 5.4 times and a compressive strength of 96 newtons per briquette (N/P). The cured CBBs reached a compressive strength of 3396 N/P and a tumbler index (TI) of 90.57%, meeting the basic cold-strength requirements for BF burdens. The high-temperature compressive strength reached a minimum of 2009 N/P at 500 °C. Interfacial reactions between the inorganic binder component and the concentrate formed strengthened bonding and supported strength retention. Based on these results, a low-temperature preparation flow of iron ore concentrate-based CBBs was summarized. Under the simplified accounting boundary, the estimated CO 2 emission was 36.59 kg·t -1 , indicating potential emission reduction compared with sintering and pelletizing. This work clarifies the processing-structure-property relationship of iron ore concentrate-based CBBs and provides mechanistic support for their further evaluation as potential low-carbon BF burdens.