Controlling the peripheral temperature of the blast furnace

Increase in FeO content lowers the initial melting temperature of primary slags in the blast furnace and prevents the formation of stable surface coatings. That increases the thermal loads on the coolers in the bosh and bosh extension and correspondingly increases the heat losses. The FeO content in the primary slags is determined by the indirect reduction. In the present work, means of reducing the thermal loads on the coolers in the bosh and bosh extension are assessed. Decrease in the gas temperature at the furnace periphery is accompanied by change in the degree of indirect reduction. Hence, the peripheral temperature may be regarded as an indicator of the degree of indirect reduction. A model of the gas temperature and the reducing effect of the gas at the furnace periphery is developed and may be used to optimize the thermal state of the furnace shaft in the peripheral zone.     

Increasing the strength of metallurgical coke by adding modified petroleum coke to the coking batch

Box-coking data show the possibility of increasing the yield and strength of metallurgical coke by introducing a coking additive in the batch. Specifically, this additive is a product of slow coking of heavy petroleum residues, characterized by excellent thermoplastic properties: clinkering properties and plastic temperature range. A Russian patent has been obtained for the coking additive.     

Formation of Phases upon the Mechanosynthesis and Subsequent Annealing of Samples of Cementite Composition Alloyed with Chromium and Nickel

Using X-ray, Mössbauer, and magnetic measurements, the formation of phases has been investigated upon mechanosynthesis in a ball planetary mill and upon the subsequent annealing of samples of the cementite composition (Fe_0.95–уСr_0.05Ni _y )₇₅C₂₅, where у = 0–0.20, which contains two alloying elements (chromium and nickel). It has been shown that, in the mechanosynthesis process, cementite alloyed with chromium and a small amount of nickel and an amorphous phase alloyed with chromium and nickel have been formed. Upon heating above 300°С, the amorphous phase is crystallized into nickel-enriched cementite. In the process of annealing at higher temperatures, the most nickel-rich cementite decomposes with the formation of austenite. As a consequence, after annealing at medium temperatures, the composition of the alloys contains cementite alloyed mainly with chromium and some amount of alloyed austenite, which can be found in ferromagnetic or paramagnetic states depending on the Ni content. Annealing at 800°С bring about the complete or partial decomposition of cementite contained in the alloys. The intensity of the decomposition has been determined by the nickel content in the samples.     

Concrete lining for steel ladle of the infusion (teapot) type

Conclusions As a result of replacing firebrick and chrome -magnesite brick by concrete of magnesite-chromite composition, the service life of the lining was increased with a simultaneous reduction of the labor force for the process.The life of the concrete lining of the ladles reaches 50–100 melts and is determined by the life of the baffle of the infusion channel, which is a battle wall and takes the jet of metal.Registered by the Committee for inventions and innovations of the Council of Ministers, USSR as No. 32408 with priority from October 31, 1962.     

The possibility of testing the structural state of highly-deformed high-carbon steels by the magnetic method

The influence of cold plastic deformation on phase transformations and on the magnetic properties of powder specimens of the Fe-5-at. % C alloy modeling U12 high-carbon steel has been investigated in the context of nondestructive testing. It has been shown that under high plastic deformation dissolution of cementite Fe3C occurs by the scheme -Fe + Fe₃C -Fe + (Fe₃C)_d + -Fe + Am(Fe-C). An increase in the rate of plastic deformation of powders decreases the coercive force from 50 to 13 A/cm due to the low coercivity of the #x03B1;-Fe and Am(Fe-C) phases. The structural state of high-carbon steels following a strong cold plastic deformation can be determined by measuring two magnetic parameters: the coercive force, and the temperature dependence of differential magnetic permeability.Translated from Defektoskopiya, Vol. 40, No. 7, 2004, pp. 42–52.Original Russian Text Copyright © 2004 by A.I. Ulyanov, Arsenteva, Zagainov, A.L. Ulyanov, Elsukov, Dorofeev.     

Effect of Structure and Phase Composition on Coercive Force and Saturation Magnetization of Mechanically Alloyed Fe100 – xCx (x = 25, 32) Powders

Mechanical fracture of iron and graphite powders leads to formation of the amorphous Fe–C phase and subsequent precipitation of the Fe₃C carbide in the Fe(75)C(25) system and Fe₃CFe₇C₃ carbide in the Fe(68)C(32) system, which are in strongly strained states. After annealing, carbides with undistorted structures are formed, and their content is higher. On the initial stage of this mechanical alloying, the magnetic characteristics of these structures are determined by their defectiveness, and on the subsequent stages of fracturing and annealing by the types, quantities, and structural conditions of the resulting carbide phases.     

Structural and phase transformations during heat treatment of the Fe(71.4)Si(14.3)C(14.3) amorphous alloy prepared by mechanical alloying

Differential scanning calorimetry, X-ray diffraction, Mössbauer spectroscopy of ⁵⁷Fe nuclei, magnetic measurements, and different heat treatments have been used to study the sequence and mechanisms of solid-state reactions in the Fe-Si-C amorphous alloy in the course of the structure transition to equilibrium. Three stages of structural and phase transformations have been found; these are the structural relaxation, formation of an Fe₅SiC silicocarbide, and its decomposition. It has been shown that the second and third stages occur during isochronous annealing within sufficiently narrow temperature ranges of 380–405 and 530–555°C, respectively. The kinetics of the decomposition of the metastable Fe₅SiC silicocarbide and the formation of the ordered Fe-Si alloy during isothermal annealing has been studied.     

Operation and maintenance of coke furnaces

Presentations at the annual seminar of specialists in coke production are analyzed, to highlight the obstacles to improvement in the reliability and longevity of existing, reconstructed, and newly built coke batteries.