METHOD OF PREPARING NITROGENIZED FERROALLOYS Russian patent published in 2002 - IPC

FIELD: ferrous metallurgy. SUBSTANCE: nitrogenized ferroalloys including those with low exothermal nitride formation effects are prepared by self-distribution high-temperature synthesis. In particular, ferroalloy to be nitrogenized is disintegrated and poured into container with gas-permeable walls to the height of the blend ingot to be formed and composed of ferroalloy powder and ignition mixture. Container is placed in reactor and burning is initiated by ignition mixture while nitrogenization proceeds in burning mode at elevated nitrogen pressure. Ignition mixture is axially charged into container in amounts between 3 and 20% based on the weight of ingot being formed. Ferroalloy powder is located round the ignition mixture with a gap relative to reactor walls. Initiation of burning reaction is performed at nitrogen pressure 70-90 atm thereby forming cylindrical flame front. After that, supplementary nitrogen is fed into reactor and its pressure is maintained within 100-150 atm. EFFECT: enabled preparation of nitrogenized ferroalloys for alloying any marks of steel both with low and high exothermal effects of nitrogen compound formation, and also increased process efficiency allowing industrial manufacture of large-size ingots.