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Kryvyi Rih, Krivoi Rog - Inguletsky, Saksagan, Pervomaisk, Annovsk, Zheltorechensk, Popelnostovsk, Novokryvorizke, Valyavkinske, Kirova |
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Ukraine |
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Fe
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Super Porphyry Cu and Au
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The Kryvyi Rih or Krivoi Rog (as it was known in Russian) iron ore deposits, within the Kryvyi Rih Iron Basin (Krivbass), is located approximately 330 km southeast of Kyiv/Kiev and 150 km north of the Black Sea in the Ukraine.
Iron ore has been known in the Kryvyi Rih district since at least 1781, although it was also known to the 'ancients'. By 1881, sufficient ore at grades of ~70% Fe, with associated manganese, had been indicated to begin industrial extraction. By 1884, >0.10 Mt of iron ore had been mined, and a 505 km railway constructed from Yasynuvata station via Kryvyi Rih to Dolynska station. Production expanded rapidly in the following years, and by 1896 there were 20 mines producing over 1 Mt of ore in the Kryvyi Rih Basin. Expansion continued up to 1917, when production dropped during the first world war and during the various conflicts of the Bolshevik Revolution. The USSR began planning of an integrated steel plant in 1929 to take iron ore and coal all the way to finished steel products, and in August 1934 the first metal was produced at Kryvorizhstal. Prior to the onset of the second world war, the complex operated 3 blast and 2 open hearth furnaces along with a heat and power plant. In 1941 a blooming mill of 1.7 Mtpa, a fourth blast and third open hearth furnace came on line shortly before Nazi occupation. Before occupation, the workforce was evacuated and during the German administration, from the August 1941 to February 1944, the plant was destroyed. Following the recapture of the area, the operation was rebuilt and progressively expanded, culminating in installation of the largest blast furnace in the world in 1974. In 1996, following Ukrainian independence, restructuring took place, and in 2004 the operation was privatised. The first privatization agreement was dismissed in court in June 2005, and a second round concluded in 2005, as detailed towards the end of this record.
The deposits of the Kryvyi Rih/Krivoy Rog region within the Ukrainian Shield and the Kursk Magnetic Anomaly on the Voronezh plate in SW Russia form a single gigantic metallogenic province of possibly correlative sequences. The iron-formation succession at Kryvyi Rih/Krivoy Rog consists of seven members having a total thickness of ~1300 m, whereas that of the Kursk area comprise five members having a thickness of ~500 m (Alexandrov, 1973).
It lies within the valley of the Ingulets River and its tributaries, the Saksagan and the Zheltaya, and extends in a NNE direction over an interval of about 100 km. The basin is developed within the crystalline basement of the Kurainian massif, comprising Archaean gneisses, granites, migmatites, amphibolites and schists exposed to the west and east of the 2200-2000 Ma Palaeoproterozoic Krivbass geosyncline. The Proterazoic Krivoi Rog Series within the Krivbass is divided into three sections:
i). a lower arkose-quartzite and phyllitic sequence, with a horizon of talc schists,
ii). a middle, ore-bearing ferruginous quartzite (banded iron formation - BIF) and slate sequence, which includes includes nine BIF horizons intercalated with quartz-sericite, chlorite-sericite, slates and microquartzites; and
iii). an upper, quartzite-sandstone-slate sequence with lenses of marble.
The Krivoi Rog Series is folded itno a complex synclinorial structure of synclinal and anticlinal folds with dips on the limbs of 45 to 80°, for the most part with a keel shaped synclinal closure plunging at up to 40° northwards. The limbs of the major synform has been intruded by Proterozoic granite and are cut by longitudinal faults or overthrusts, resulting in the ore-bearing units being segregated along the north-south strike of the basin to form the: i). southern-most Inguletsky, ii). the Saksagan or Main, iii). the Pervomaisk, iv). Annovsk, and v). the northern Zheltorechensk and Popel'nostovsk ore fields. The largest reserves of high grade ores are concentrated in the Saksagan ore field where the ore-bearing middle unit attains a thickness of up to 2000 m and contains up to eight BIF seams.
The BIFs (locally termed 'ferruginous quartzites') comprise magnetite, magnetite-hematite, and hematite varieties, the most economically significant being the unoxidized magnetite and magnetite-hematite varieties. The high grade ores consist mainly of iron oxides and hydroxides which form column-like, less commonly stock-, and lens-like, and more rarely layer-like segregations and bodies within the BIF units, the characteristics of which vary from location to location within the basin. This high grade ore was formed by the leaching of quartz and oxidation of iron silicates within the BIFs.
The high grade segregations are commonly localised on the limbs of the major folds where those limbs are deformed by tranverse cross-folds and 'crumpling', accompanied by the development of cleavage and interstratal movements, strike-slip faulting, fracture intersections and in zones of fracturing, crushing and jointing. They form chains with larger or smaller accumulations, with the individual ore bodies apparently merging at depth in the keel of the syncline to form large ore columns coinciding with the fold keels.
The richest concentrations of ore in the main Saksagan ore field are associated with the fifth and sixth BIF units, which contain higher grade primary mineralisation, and have thinner bedding which contributed to the development of the deformation. The ore segregations are located totally within the BIF units, on the limbs and within the keels of the synclines. In the Southern ore fields, concordant planar ore layers are localised in the unconformable contact between the middle and upper sections of the Krivoi Rog Series. In the Northern ore fields, the ores have been hydrothermally-metasomatically altered.
High grade hypogene magnetite-hematite jaspilite polished slab from the Inguletsky Mine, Kryvyi Rih. It is strongly magnetic, mainly composed of pale- to mid-grey magnetite and red hematite bands with very little silica. Sample collected 1994. Image by Mike Porter, 2022.
Four principal types of enriched ores have been recognised in the Krivbass group, as follows:
i). Martite and hematite-martite - in addition to martite and relict hematite, relict magnetite, dispersed hematite, chlorite, sericite, pyrite, carbonates, clay minerals, quartz, and apatite have been observed in small amounts. The average content of this ore style is recorded at 63.7% Fe, 0.26% P, 0.043% S;
ii). Martite-hematite-hydrohematite-hydrogoethite - in addition to the assemblages listed above, there are also dispersed hematite, martite, sericite, quartz, clay minerals, alunite and sphene in small and accessory amounts. The average content of this ore style is recorded as 62.3% Fe, 0.08% P, 0.03% S;
iii). Hematite-hydrohematite-hydrogoethite - in addition to the main ore minerals, there is kaolinite, clay minerals, chlorite and carbonates. The average content of this ore style is recorded as 57.5% Fe, 0.088% P, very low S;
iv). Magnetite and magnetite-specularite - in addition to the dominant magnetite and specularite, amphiboles (curnmingtonite, grunerite, and riebeckite), aegirine, biotite, albite, quartz, carbonates, chlorite, grains of pyrite, pyrrhotite and chalcopyrite, have been recorded. The average content of this ore style is recorded as 54.0% Fe, 0.04% P, 0.15% S.
The original resource of high-grade iron ore within the Krivbass totalled 19.6 Gt (including 4 Gt @ 57.6% Fe), plus and additional 18 Gt of unenriched BIF averaging 35.9% Fe (Smirnov 1977).
Most of the higher grade ore had been exhausted by 1990 when the annual production was 186 Mt @ 35.2% Fe.
In 2005, after an initial privatisation in 2004, Mittal Steel acquired the Ukrainian entity Kryvorizhstal which became ArcelorMittal Kryvyi Rih, and included mining and steel making operations. In 2020, the company operated a concentrating facility, along with two open pit sites and one underground iron ore mine. The iron ore deposits are located within the southern part of the Krivorozhsky iron-ore basin. The concentration process includes crushing, grinding, classification, magnetic separation and filtering.
ArcelorMittal Kryvyi Ri's iron ore base comprises ferruginous quartzite of Novokryvorizke and Valyavkinske deposits, mined from two open pits, #2 and #3, and the high-grade Kirova deposit which is processed into lump and sinter ore. In 2020, actual production was 10.7 Mt of concentrate and 0.6 Mt tonnes of sinter feed.
Remaining Ore Reserves and Mineral Resources as of December 31, 2020 (ArcelorMittal 2020 Annual Report) were:
Open pit - includes magnetite ore only
Proved + Probable Reserves - 583 Mt @ 34.3% Fe;
Measured + Indicated Resources - 741 Mt @ 30.1% Fe;
Inferred Resources - 62 Mt @ 30.0% Fe.
Underground - includes martite and jaspilite
Proved + Probable Reserves - 27 Mt @ 54.4% Fe;
Measured + Indicated Resources - 38 Mt @ 56.8% Fe;
Inferred Resources - 25 Mt @ 55.4% Fe.
NOTE: Resources are exclusive of Reserves.
Reserves and Resources are based on the Ukraine State Committee on Reserves, GKZ standard, where Category A+B is equivalent to “Proved” and C1 is equivalent to “Probable” reserves. Proved and Probable iron ore reserve estimates are typically based on a drilling densities ranging from 25 x 25 to 100 x 100 m, and 50 x 50 to 300 x 300 m respectively. Inferred mineral resource estimates are based on drill hole spacing ranging from 100 x 100 to 500 x 500 m.
The most recent source geological information used to prepare this decription was dated: 1993.
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd. Unauthorised copying, reproduction, storage or dissemination prohibited.
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Selected References:
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Alexandrov E A, 1973 - The Precambrian banded iron formations of the Soviet Union: in Econ. Geol. v68 pp 1035-1062
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Findlay D, 1994 - Diagenetic boudinage, an analogue model for the control on hematite enrichment iron ores of the Hamersley Iron Province of Western Australia, and a comparison with Krivoi Rog of Ukraine, and Nimba Range, Liberia: in Ore Geology Reviews v9 pp 311-324
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Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge. It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published. While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo, its employees and servants: i). do not warrant, or make any representation regarding the use, or results of the use of the information contained herein as to its correctness, accuracy, currency, or otherwise; and ii). expressly disclaim all liability or responsibility to any person using the information or conclusions contained herein.
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