SU985054A1 - Method of producing transformer steel - Google Patents

Description

 by increasing the fraction of oxygen in the argon-oxygen mixture, increases the duration of the refining process, and reduces the plant capacity.

The purpose of the invention is to increase the productivity of the process.

The goal is achieved by the fact that in the method of steel production, including pouring iron, blowing oxygen to carbon content of 0.050, O8%, releasing metal into an intermediate tank, blowing with argon-oxygen mixture with a constant decrease in the oxygen content in it, pouring metal into the steel casting ladle, deoxidation , alloying and casting of steel, purging with an argon-oxygen mixture is carried out, increasing step by step its consumption from 0.9-1.0 mLCH with carbon content O, O5-O, O8% to 1.7-2.0 with carbon content 0.005- 0.03% and support oxygen consumption They are constant within O, 45-O, 55.

The essence of the invention is that an increase in the consumption of argon-oxygen mixture in a certain way compensates for the relative decrease in its oxidative potential, allowing

. to intensify the process of carbon oxidation, retaining at a fairly low level the oxidation of metal and slag.

In a steelmaking unit, for example, an oxygen converter, cast iron is poured and oxygenated to carbon content O, O5-0, O8%. The unspanded metal is drained from the converter into an intermediate tank, for example, a steel-working ladle, where the metal is blown with an argon-oxygen mixture through, for example, a porous magnesite lance installed in the bottom of the casting ladle. To reduce the oxidation of the metal and slag, the oxygen fraction in the argon-oxygen blast gradually decreases, for example, from the ratio between oxygen and argon 1: 1 at the beginning of the purge when the metal content is 0.06-0.08% carbon to the ratio 1: 3 at the end of the purge when the content is carbon 0,005-0,03% In the process of blowing at a simultaneous cj by reducing the proportion of oxygen in the blast, the flow rate of the argon-oxygen mixture increases from 0.9-1.0 to 1.7-2. At the same time, the volume of oxygen injected into the metal remains constant throughout the entire purge and is equal to 0.5 m / t-h, and the decrease in the fraction of oxygen in the blast is ensured by a corresponding increase in the argon consumption. In this case, although the oxidation potential of the mixture of injected gases is reduced, however, the absolute amount of oxygen supplied to the metal per unit time is increased unchanged. This provides a certain increase in the rate of oxidation of carbon and a corresponding reduction in the duration of the treatment of the metal with an argon-oxygen mixture of gases.

The intensity of the purging of the metal with an argon-oxygen gas mixture determines the rate of the decarburization process and is lithiated by the free volume of the intermediate capacity.

With a high intensity of purging (over 2.0), a large volume of p-gz separating from the metal causes an increase in its volume and overflow over the edge of the intermediate tank. In turn, the volume of the intermediate capacitance is limited by the thermal possibilities of the converter. With an increase in the volume of the tank, the mass of refractories increases, the heating of which requires additional heat, and therefore a significant overheating of the metal in the converter. On the other hand, the volume of gases emitted from Mfetal depends on the oxidation rate of carbon. It is known that with a decrease in carbon content, the rate of its oxidation also decreases, and especially sharply with a low carbon content in the melt. Thus, for example, with a decrease in the carbon content in the molten iron from O, O8 to 0.02%, the oxidation rate of carbon decreases more than twice, and accordingly, the volume of gases leached from the metal decreases approximately twice. Due to this, it is possible, as the carbon content in metal j decreases, to increase the consumption of argon-oxygen blowing (from 0.9-1.0 at a carbon concentration of 0, O5-O, 08% to 1.7-2, Ohm / t – h when carbon in the metal is less than 0, OZ%) without fear of overflow. metal over the edge of an intermediate tank.

To achieve the required carbon content, the metal is poured into the second steel-pouring ladle, where it is oxidized and alloyed, after which the steel is cast, for example, through molds.

Primer p. An EPA transformer steel is smelted in a 140 ton oxygen converter. The purging of the metal with oxygen in the converter is completed when the carbon content in the metal is 0.06-0.08%. Intermediate with such

carbon content from convergger & 1 steel teeler equipped with porous magnesite with tuyere. Bringing the steel to the required carbon content (0.024-0.026%) production (1T in 1 ladle by purging metal with an argon-oxygen mixture. Purging is carried out with a mixture of argon and technically pure oxygen with a purity of at least 99.5% with a dassen of 7-8 atm for 25- 30 min.

During blown-down metal oT6i raugg samples in which the current carbon content is determined in accordance with the composition of the metal and the consumption of argon-oxygen mixture increases from 0, 9-1, O to 1.7-2.0 according to the scheme.

The data presented in Table. one.

An increase in the purge intensity from 1 to 2, despite the decreasing oxidation potential of blowing, increases the oxidation rate of carbon, provides a reduction in the duration of the purge period and an increase in the throughput of the plant.

In tab. 2 shows the change in the duration of the purge of the transformer steel argh-oxygen mixture) with the decomposition and intensity P of the same fraction of oxygen in the blast

The metal, brought to a given composition, is deoxidized and alloyed with FS-69 grade ferrosilicon to calculate the introduction of 3% curviline into steel and poured it into iron.

The economic effect of trr real zashga of this method with a volume of 450 tyu.t transformer steel per year is 225 thousand rubles.

Tablida

Purge mode

,.Table 2

Duration hfo uyezh transformer steel

1: 3

1.0

1: 1 1.2 1: 1 1: 3 argon-oxygen mixture of gases

0.024

Not

Claims (3)

35 30 O, O23 Emissions Formula of the invention A method of producing transformer steel, including pouring cast iron, blowing oxygen. To the carbon content of O, O5-O, O8%, releasing metal into an intermediate tank, blowing argon-oxygen with a mixture with a constant decrease in oxygen, metal overflow into the ladle, deoxidation, alloying and casting of steel, characterized in that, in order to increase the productivity of the process, argon-oxygen blowing D) VOYO4 8 Prodophy t (tpl. 2 mixture lead, increasing step by step, its consumption from 0.9-1.0 with a carbon content of 0.05-0.08% to 1.7-2, with a carbon content of 0.005-0.03%, and the oxygen consumption is kept constant within the limits of O, 45, U, 55 MVT-h. Sources of information taken into account during the examination 1. USSR author's certificate No. 603674, KL.S21S 7/00, 1976. 2. USSR author's certificate number 499319, cl. C 21 C 5/52, 1974. 3. USSR author's certificate number 379633, cl. C 21 C 5/52, 1971.