METALLOINVEST is a leading global iron ore and HBI producer based in Russia

  • The world’s largest iron ore deposits under operation
  • The biggest regional iron ore production ranking in the top5 globally
  • The biggest HBI supplier globally
  • Strategic location of the main producing assets in Russia’s European part
  • Global leadership in iron ore production cost efficiency
  • One of the major steel producers in Russia

Technology

Mikhailovsky GOK’s technological process includes the following stages:

Iron ore mining
Lose overburden excavation is carried out by means of walking dragline excavators ESh 10/50. Loose overburden is transported by means of railway transport to the external dumps and partially to the works for construction material production.  Blasthole drilling in the high-grade zones is performed by rigs SBSh-250MNA. In the low-grade zones to enhance the explosive energy the drilling holes are enlarged with thermal drilling rigs SBT-400MNR.

The drill holes are charged with standard explosives (such as trotyl, ammonite, etc.), as well as with granemite — an explosive of Mikhailovsky GOK’s own making which is charged with the mobile mixing and charging machines (TSZM). Rock overburden excavation is performed by EKG excavators with further loading into dump trucks BelAZ, Komatsu and Euclid with the capacity ranges from 120 to 136 tons. High and low grade ore transloading into railway transport is realized on internal transfer points with further transportation to the Crushing and Sorting Plant.

Rock overburden is loaded into large dump trucks and partially delivered to the internal transfer point and further by railway transport to the Crushing and Sorting Plant for production of commercial road stone and to the external oxidized quartzites stockpile, partially it is transported by large dump trucks to the internal stockpiles.

Production of Sintered Ore and Blast-Furnace Ore
(Crushing and Sorting Plant, CSP).
High-grade ore is transported to the Crushing and Sorting Plant where it is used for production of sintered and blast furnace ore. There are three stages of ore crushing with preliminary screening in each stage. The 3rd stage of crushing is performed in closed circuit, the crushed product is recycled to the preliminary screening. The primary process equipment is jaw crushers (stage 1) and cone crushers (stages 2 and 3), unbalanced throw screens and belt conveyors.

High-grade ore with mass fraction from 10 to 70 mm and 42–43% Fe content undergoes the beneficiation process and is shipped to the consumers as blast furnace ore.

The material with the lump size over 10 mm is blended both directly during the process and during the layering while stacking on the stockyard. This product contents 52-53% Fe and is shipped to the consumers as sintered ore. Sintered ore moisture is 7–8 %. In winter period taking into account the needs of consumers in Urals and western Siberia the produced sintered ore has the moisture up to 3%.

Drying section of the Crushing and Sorting plant is partially used for drying of magnetite concentrate coming from Crushing and beneficiation Plant, which allows extending market outlets during winter period. As frequently demanded by consumers, blast furnace concentrate is also produced during winter season. It is a mechanical mixture of dried sintered ore and concentrate of the specified ratio.

Production of concentrate
(Crushing and Beneficiating Plant, CBP)
The low-grade ore (non oxidized quartzites) is delivered to the Crushing and Beneficiating Plant in dumping wagons, the maximum lump size is 1,000 mm.

Ore is crushed with cone crushers in four stages in the open circuit. The standard size product is preliminary separated upstream stage III and stage IV.

The weighted average lump size of the final product, that is crushed ore, is 9–10 mm. Crushed ore fed to the bin of beneficiation section with system of belt conveyors. Crushed ore is then fed with belt conveyors to dry magnetic separation located before crushing stage I. Magnetic product of dry magnetic separation is conveyed to stage I crushing whereas tails are conveyed to the screening section to separate broken stone and undersize (fines).

Undersize is partially realized as the marketable product, and is partially used for internal needs, the remaining residue is transported to the external dump. Broken stone is sold as marketable product with natural lump size or, in addition, undergoes class separation on the Crushing and Sorting Plant.

Grinding of magnetite product of dry magnetic separation is performed by three stages, using wet grinding ball mills with the ball diameter of 120, 60 and 40 mm respectively. Spiral classifiers and hydrocyclons of 500 and 360 mm are utilized for classification.

The beneficiation includes three stages of wet magnetic separation and two stages of desliming. For that purpose magnetic separators for wet separation and magnetic deslimers are used. Tails in the form of pulp are transported to the tailing pond by means of soil pumps. Dewatering is performed in disc vacuum filters. Here air and excessive moisture is forced through filter cloth. Current concentrate has around 65% Fe, the residual moisture is 9.5–10%. Magnetite concentrate is partially sold as a final product to steelworks and partially goes to the Crushing and Sorting Plant as feed for dried and blast furnace concentrates, and also goes to the Pellet Plant for production of fluxed pellets.

Production of Pellets
Pellet Plant (PP)
In the Pellet Plant for production of fluxed pellets ground limestone is used as fluxing agent, and bentonite is used for moisture adsorption and providing green pellets with required mechanical and physical properties.

Pelletizing is carried out in drum pelletizers after careful mixing of burden material, the diameter of produced green pellets is about 10–16 mm.

To achieve the required hardness, green pellets are fired in the conveyor indurating machines. Green pellets are loaded by uniform layers onto machine pallets, after that they undergo several zones, beginning with drying, then firing and cooling. Gas streams temperature in the firing zone reaches 1,200°С, natural gas is used as heat-bearing agent. Pellets compression strength after firing is 250– 260 kg/pellet.