Minerals

Vanadium–titanium magnetite is a strategically important resource for iron, vanadium, and titanium production, yet its utilization in conventional blast furnace–basic oxygen furnace routes is limited by the dilution of titanium into low-value slag. This study investigates an integrated process route combining pellet preparation, hydrogen-based shaft furnace reduction conducted in the temperature range of 800–1000 °C, and subsequent electric furnace smelting for efficient recovery of Fe, V, and Ti. Pellets prepared from 100 wt.% vanadium–titanium magnetite exhibited sufficient mechanical strength but showed poor reducibility and severe low-temperature reduction disintegration, rendering them unsuitable for hydrogen-based shaft furnace operation. To overcome these limitations, systematic ore blending was applied. An optimized pellet composition comprising 40 wt.% vanadium–titanium magnetite, 50 wt.% high-grade iron ore, and 10 wt.% titanium concentrate achieved reduction degrees above 90%, acceptable swelling and bonding behavior, and low reduction disintegration indices meeting industrial HYL requirements. Industrial trials in a hydrogen-based shaft furnace demonstrated stable operation and consistent product quality, producing direct reduced iron with controlled metallization and enrichment of titanium and vanadium. Subsequent electric furnace smelting achieved clear slag–metal separation, yielding hot metal with high iron and vanadium recovery and a TiO₂-rich slag containing approximately 45 wt.% TiO₂. Recovery rates of Fe, V, and Ti exceeded 90%, confirming the technical feasibility of the proposed process route.

The North China Craton (NCC), one of the oldest cratons worldwide, may provide information on the evolution and geodynamic processes of the early Earth, especially during the pre-Mesoarchean period. Many ancient zircons have been discovered in the Jiapigou terrane of the northeastern NCC on the basis of our recent studies, providing an excellent opportunity to trace the early crustal evolution trend of the NCC. Here, we present a detailed study of the petrography, mineralogy, zircon U–Pb dating and Lu–Hf isotopes of supracrustal rocks (biotite schist) obtained from the Jiapigou terrane. Geochronology combined with the internal structures and Th/U ratios of the zircons reveal that the zircons acquired from the supracrustal rock can be divided into the following two types: magmatic zircons and metamorphic zircons. Among the magmatic zircons, the youngest zircon age (2.49 Ga) is considered to represent the time at which the protolith of the supracrustal rock (i.e., Neoarchean) crystallized, whereas the others were likely captured or inherited from their magma sources. The zircon Hf isotopes reveal that unexposed Hadean–Paleoarchean crust (4.18–3.57 Ga) is present beneath the Jiapigou terrane, and its growth history can be traced back to the Hadean period. Moreover, the evidence derived from this and previous studies indicates that the Jiapigou terrane underwent two crustal recycling events (3.37–3.20 Ga and ~2.96 Ga) during the Paleoarchean, two crustal reworking episodes (2.53 Ga and 2.49 Ga) during the Neoarchean, and later metamorphism at 2.41 Ga. Thus, the Jiapigou terrane has undoubtedly recorded multiple episodes of early crustal growth and/or reworking that are similar to, but not limited to, those of the northern and southern margins of the NCC.

Late Cretaceous plutonic rocks are commonly observed along the Southeastern Anatolian Orogenic Belt (SAOB), which constitutes a significant part of the Alpine–Himalayan Orogenic Belt. Here, we present new whole-rock geochemical analyses, zircon U–Pb ages, and zircon trace element data of plutonic rocks located in the SAOB (eastern Türkiye). This study aims to determine the petrogenesis of the studied plutonic rocks in light of new data and to contribute to the tectonic evolution of the SAOB. Geochemical data demonstrate that the studied granodiorites, diorites, and gabbros are tholeiitic–calc–alkaline in composition, metaluminous, and I-type granite. Zircon U-Pb ages yielded crystallisation ages of 73.52 ± 0.24 Ma for the studied granodiorites and 78.86 ± 0.39 Ma for the diorites. These age data indicate that the studied plutonic rocks represent the youngest granodiorite and diorite formations observed around the study area. High Th/U ratios (granodiorite: 0.15–0.29; diorite: 0.31–0.96) and positive Ce/Ce* (granodiorite: 8.11 to 609.86; diorite: 58.07 to 564.31) and negative Eu/Eu* (granodiorite: 0.49 to 0.62; diorite: 0.59–0.97) values obtained in zircon grains suggest that they are of magmatic origin. Geochemical data indicate that the studied diorites and gabbros originate from a spinel-bearing source representing shallow depths. In light of all the data, the studied plutonic rocks are products of arc magmatism resulting from the subduction of the NeoTethys Oceanic lithosphere along the SAOB.