OAO NTMK Research Articles

RH-Degasser Refractory Corrosion Mechanism by Lime-Silica Slags of Different Basicity

Results are provided for a laboratory study of the reaction of industrial self-dissociating slag after steel treatment in an OAO NTMK furnace-ladle unit and synthetic slag of the system CaO–SiO2–Al2O3 with five forms of periclase-spinelid refractories produced by enterprises of Gruppa Magnezit in Russia and Slovakia (Slovmag), and also two Chinese producers. Refractory slag resistance is compared, and their mineral and phase compositions are studied before and after testing.

Brickwork of furnace lining of high-temperature metallurgical plants produced from special refractory materials

The feasibility of applying specially designed refractory articles is demonstrated. Through the use of such articles it is shown that it is possible to reduce the thermal stresses that are experienced in the use of lining, markedly reduce separation of refractory products, and reduce heat losses through the brickwork by virtue of the presence of a heat-insulating layer in a given article consisting of refractory material and artificial pores as well as gaps for placement of additional heat insulation. These types of refractory products may be compacted and either roasted or unroasted and may also be manufactured according to the technology used in the fabrication of concrete. A press mold has been produced and put into production at the refractory plant of OAO NTMK for the purpose of fabricating specialized articles. The articles have successfully undergone tests, introduced into the crown of open-hearth furnaces, and are used for lining of rotary furnaces. The life of the linings was increased 1.3 – 1.4-fold

Analysis of various versions of the deoxidation of rail steel at OAO NTMK

The deoxidation of steel melted using various types of deoxidizers during out-of-furnace treatment is studied. The total oxygen and nitrogen content and the oxygen contents in the main types of oxide nonmetallic inclusions are determined by fractional gas analysis of steel samples taken from heats performed by various schedules. The main types of nonmetallic inclusions and their size distributions are found with qualitative and quantitative metallography. The oxygen content in the rail steel is minimal (5 ppm) when calcium carbide CaC2 is introduced into the metal in tapping of a converter. When the metal is deoxidized using a steel wire filled with calcium or a steel wire filled with silicocalcium, the oxygen content in rail steel is ≈8 and ≈11 ppm, respectively. A comparison of various processes of rail steel deoxidation under the OAO NTMK conditions shows that the limitation of the aluminum content (no more than 30 ppm) or the use of a wire with a calcium or calcium carbide filler is more effective than the use of a wire filled with silicocalcium.

Quality requirements on coke for blast furnaces operating with coal-dust fuel

Analysis of the CSR values of coke corresponding to specific consumption of coal-dust fuel—on the basis of operational data for furnaces in the United States, Canada, Belgium, Germany, France, Italy, Spain, and South Korea—permits the estimation of the mean CSR value of coke required when the coal-dust injection is 120, 130, 150, 180, and 200 kg/t of hot metal. This information is used in the construction of systems based on coal-dust fuel at OAO Severstal, OAO NLMK, OAO NTMK, and OAO ZSMK.

Efficiency of selective crushing with pneumatic separation for the third unit in the OAO NTMK coal-preparation shop 2. Equipment and operating conditions

The efficiency of selective crushing with pneumomechanical separation is investigated as a function of the quality of the coal batch and the operating conditions of the fluidized-bed separator.

Optimizing the ladle treatment of rail steel at OAO NTMK

Rail steel production at OAO NTMK has a number of distinguishing features. The intermediate metal is smelted in the converter in two stages: first, the production of the intermediate metal and vanadium slag; second, the correction of the intermediate metal’s chemical composition to meet grade requirements. Then the metal is sent for ladle treatment, including reduction and alloying of the melt after discharge in a ladle‐furnace unit under slag, with argon injection; and vacuum degassing of the metal in the ladle under slag (in an RH circulation unit), prior to continuous casting.

Using calcium carbide to reduce steel in the converter shop at OAO NTMK

Using calcium carbide to reduce steel in the converter shop at OAO NTMK

New system for supplying friable materials to the converter shop at OAO NTMK

New system for supplying friable materials to the converter shop at OAO NTMK

Extending the life of rail made from OAO NTMK converter steel

Extending the life of rail made from OAO NTMK converter steel

Continuous casting of steel at OAO NTMK

Continuous casting of steel at OAO NTMK

Optimizing the coking coal employed at OAO NTMK to ensure competitive CSR and CRI values of coke

Optimizing the coking coal employed at OAO NTMK to ensure competitive CSR and CRI values of coke

OAO NTMK coking coal and its compliance with blast-furnace requirements

OAO NTMK coking coal and its compliance with blast-furnace requirements