Abstract—

The experimental works of Russian and foreign researchers focused on the behavior of ore minerals, such as titanomagnetite and ilmenite in an oxidizing environment in different temperature ranges, have been analyzed. The optimum temperature conditions and time interval for oxidizing roasting of mineral aggregates have been substantiated. The Medvedevskoe ores are described in brief. Special attention is paid to the mineral assemblages of disseminated titanomagnetite–ilmenite ore subjected to secondary alterations, such as amphibolization, chloritization, saussuritization, albitization, and martitization. The evolution of the phase and structural heterogeneity of titanomagnetite microaggregates is observed as variations in the composition and structure of magnetite–ilmenite exsolution products under collective recrystallization complicated by martitization processes. Oxidizing roasting (T = 1000–1100°C) of titanomagnetite aggregates makes it possible to reduce the degree of their heterogeneity and form stable mineral phases, such as pseudobrookite, hematite, and rutile with subsequent enlargement thereof. The heterogeneous structure of titanomagnetite microaggregates affects the course of heterogeneous oxidation processes in microaggregates of different mineral assemblages. Due to solid-phase transformations, martitized titanomagnetite (with ilmenite lamellae) changes completely with the formation of pseudobrookite–hematite microaggregates. Ilmenite at the contact with hematite, as well as in individual grains, is transformed into complex fine-grained rutile–pseudobrookite aggregates. The newly formed minerals are mostly solid solutions. Pseudobrookite is characterized by a reduced Fe₂O₃ content (up to 62.71 wt %) with 33.51 wt % TiO₂. Hematite as an transformation product of martitized magnetite contains up to 4.90 wt % TiO₂. Rutile forms limited solid solutions with pseudobrookite, and Fe₂O₃ reaches 7.59 wt %. With a decrease in material size, the solid-phase transformation process becomes more active; therefore, the optimum size grades include –0.25 + 0.125 mm and –0.125 + 0.071 mm. The solid-phase transformation of primary ore minerals is almost completed during the roasting for 72 h. The homogenization of mineral aggregates and the enlargement of newly formed Fe- and Ti-bearing minerals makes them better detectable in technological products and improves the general Ti extraction in various products. The results obtained in the course of high-temperature oxidizing roasting of magnetite–ilmenite ores at the Medvedevskoe deposit can be of interest to geologists studying the formation processes of magmatic magnetite–ilmenite deposits, which vary widely in terms of both mineralization composition (from low-grade Ti ores to extremely hard-to-process high-grade Ti ores) and formation conditions (deposits of various depth facies) and depend considerably on the oxygen regime and composition of volatile mineralizing elements (H₂O, Cl, F, etc.).

中文翻译：

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在 Medvedevskoe 矿床和某些地质事件（南乌拉尔）浸染钛磁铁矿-钛铁矿氧化焙烧过程中钛磁铁矿和钛铁矿的固相转变

摘要-

俄罗斯和外国研究人员的实验工作重点分析了矿石矿物，如钛磁铁矿和钛铁矿在不同温度范围内的氧化环境中的行为。确定了矿料氧化焙烧的最佳温度条件和时间间隔。简要描述了 Medvedevskoe 矿石。特别关注经过二次蚀变的浸染钛磁铁矿-钛铁矿的矿物组合，如角闪石化、绿泥石化、苏苏石化、钠长石化和马钛矿化。观察到钛磁铁矿微团聚体的相和结构异质性的演变是由于磁铁矿 - 钛铁矿出溶产物在集体再结晶和马氏体化过程复杂化的情况下的组成和结构的变化。氧化焙烧（T = 1000–1100°C) 的钛磁铁矿聚集体可以降低它们的非均质性程度并形成稳定的矿物相，如假板钛矿、赤铁矿和金红石，并随后扩大。钛磁铁矿微团聚体的异质结构影响不同矿物组合微团聚体的异质氧化过程。由于固相转变，马氏体化的钛磁铁矿（带有钛铁矿片层）随着假板钛矿-赤铁矿微聚集体的形成而完全改变。钛铁矿与赤铁矿以及单个晶粒接触时，会转化为复杂的细粒金红石-假板钛矿聚集体。新形成的矿物多为固溶体。假板钛矿的特点是 Fe ₂O ₃含量（高达 62.71 wt %）与 33.51 wt % TiO ₂。作为马氏体化磁铁矿的转化产物的赤铁矿含有高达 4.90 wt% 的 TiO ₂。金红石与假板钛矿形成有限固溶体，Fe ₂ O ₃达到 7.59 重量％。随着材料尺寸的减小，固相转变过程变得更加活跃；因此，最佳尺寸等级包括 –0.25 + 0.125 mm 和 –0.125 + 0.071 mm。原矿矿物的固相转变在72 h的焙烧过程中基本完成。矿物聚集体的均质化和新形成的含铁和含钛矿物的扩大使它们在技术产品中更容易被检测到，并改善了各种产品中的一般 Ti 提取。在 Medvedevskoe 矿床磁铁矿-钛铁矿高温氧化焙烧过程中获得的结果可能对研究岩浆磁铁矿-钛铁矿矿床形成过程的地质学家感兴趣，₂ O、Cl、F 等）。