In order to deal with problems related to low speed and strength in coldbond agglomerations of ferrous scrap (e.g., converter mud, dust), a new rusting agent for agglomeration was proposed and studied. A fast concretion mechanism and factors influencing it were investigated. The results show that the rusting agent could increase the concretion speed and improve the agglomeration strength. When metal iron content is 5%, material moisture 10%, pressure 300 kg/cm2, and resting period 24 h, the strength of agglomeration reaches more than 2 000 N/P.