Prospects for the use of rocks of the Ergeninskaya suite for obtaining Ti-Zr raw materials (Republic of Kalmykia)

Abstract

Introduction: Titanium and zirconium are strategic minerals. Despite the fact that Russia is the world's largest source of raw materials for titanium, the contribution of the country to the world production of titanium concentrates is only 0.03%, and for the production of zirconium concentrates it does not exceed 1%. In this regard, the import substitution of Ti-Zr raw materials is necessary. The solution to the problem of shortage of Ti-Zr raw materials is the studying new promising objects and improving the extraction technology based on the waste-free, integrated use of productive sands. General information about the geological structure of the territory and the state of study: deposits of the Cenozoic age are involved in the geological structure of the region. Paleogene, Neogene and Quaternary formations come to the surface along the beams on the Ergeninsky Upland. Titanium-zirconium placers of the Ergeninsky Upland belong to the potential Ergeninsky placer area within the Ciscaucasian placer province. The Umantsevo-Maloderbetskoe, Sadovo-Obilnenskoe, Balkovsko-Kegultinskoe, Remontnenskoe and Buratinsky alluvial fields are distinguished within the Ergeninsky placer region. Conditions for the formation of a productive stratum: The genetic affiliation of the sandy sediments of the Ergeninskaya suite, which was the object of numerous studies, has not yet been unequivocally determined; different authors classify them as fluvioglacial, alluvial, deltaic, or coastal-marine formations. The structure of the Ergeninskaya formation: The vertical section of the Ergenin deposits is subdivided into three parts according to lithological-mineralogical, facies, and structural-textural features: the lower basal part (from 0.3 to 10 m) is characterized by coarse and coarse-grained sands with an admixture of gravel material. The middle part of the section (up to 20 m) is represented mainly by coarse and mediumgrained, cross-bedded sands, the layering in which is emphasized by the gradation sorting of the material and rare black sand interlayers of heavy minerals. The most productive is the upper part of the section composed of fine and fine-grained sands, 60–70% consisting of grains 0.1–0.25 mm in size with heavy fraction contents, in some parts of the section up to 3–5%. Structural and paleogeomorphological features: The analysis of the paleo-geomorphological schemes of the eastern part of the Ergeninsky placer area showed that areas of distribution of large linear erosivetectonic depressions, which were inherited by local overdeep depressions within stable morphostructures, can be considered very favourable for burial and exposure at the pre-Quaternary stage. Minerals of the heavy fraction of the Ergeninskaya formation: The results of the study of the mineral spectrum of the heavy fraction of the Sadovo-Obilnensky alluvial field, and its comparison with the known titanium-zirconium deposits in neighbouring territories, are presented. Conclusions: Recommendations on the integrated use of the Ergenin sands and the direction of further research are proposed. For example, the use of common sands with the preliminary improvement of the quality in terms of granulometric composition, reduction of clay content, release of heavy minerals, allows to obtain, in addition to building sands, glass, moulding sands, as well as a product enriched with heavy fraction minerals, including Ti-Zr raw materials and other concentrates.