Invar alloy (Fe-36mass%Ni) is widely used in precision applications due to its low thermal expansion, where ultra-high cleanliness is required. Achieving this cleanliness requires control of secondary inclusions, which is closely influenced by solute microsegregation. One of the important parameters to predict microsegregation and the subsequent evolution of secondary inclusions is determined by the partition of solute elements during solidification. However, reported studies on the partition of solute elements in Invar alloy remains limited. This study determined partition coefficient values of Ni, Si, Mn, and Al in Fe-36mass%Ni alloy using two experimental approaches: the conventional equilibrium quenching and a random sampling method. In the quenching method, alloys with varied Si and Al contents were employed for partition coefficient determination. In the random sampling method, solidification alloys prepared under cooling rates 0.65 and 5.27 K/min were employed. Multiple sorting techniques were applied, including single-element rank sorting, average rank sorting and weighted interval rank sorting. Partition coefficients were derived by fitting concentration profiles to Scheil’s equation within the solid fraction range of 0.1 to 0.8. Additionally, effect of sampling size was systematically evaluated. For Si and Mn, a standard deviation below 0.01 required more than 5000 sampling points. In contrast, Ni remains stable even at smaller sample sizes. It was found that partition coefficients obtained from different two experimental techniques, and calculated segregation profiles satisfactorily reproduce experimental data.

In iron and steel sintering production, traditional granulation processes often face poor particle aggregation uniformity and high residual fine content, which leads to large fluctuations in the permeability of the sinter bed and uneven thermal reactions. To address these issues, this study innovatively integrates the granulation process using external rolling of coke powder and quicklime with pre-wetting treatment. The study systematically explores the coupling effects of granulation moisture, rotation speed, lime addition, coke powder particle size, and pre-wetting time with carbon content and moisture in the sintering mixture. Experimental results indicate that granulation with 7%–8% moisture, 22–24 r/min rotation speed, 3.5% lime addition, 1.5–2.0 mm average coke powder size, and 3 min pre-wetting time, combined with 3.8% carbon content in the sintering step, produces granules with excellent sphericity. Under these conditions, drum strength of the sintered ore reaches 66.2%, and reduction performance is significantly improved, meeting the requirements for high-quality sintered ore. In summary, the proposed improved process and full-process parameter experimental method provide an effective approach to address the chain problem of “poor granule quality–low sintering efficiency–fluctuating ore performance” in traditional sintering. This study not only supports steel enterprises in improving sintering efficiency and reducing energy consumption but also ensures the stable supply of high-strength, high-reducibility sinter to blast furnaces, promoting more efficient and greener steel production.