SU986933A1 - Method for producing naturally alloyed vanadium steel - Google Patents

Description

(54) HOW TO GET THE NATURAL LEAGUE VANADIUM STEEL

1 The invention relates to ferrous metallurgy, specifically to methods for smelting steel in converters of vanadium-containing iron. There is a known method of steel smelting in a container of metal cones containing u) vanadium-iron-alloyed iron, which involves blowing the metal with oxygen from above and obtaining basic slag. The disadvantage of this method is that vanadium almost completely goes into slag. The closest in technical essence and the achieved result to npeib lat is a method of producing pre-alloyed vanadium steel in a converter, including pouring vanadium iron, purging it with oxidizing gas, deoxidation and loosening the metal in the converter f 2j. However, a high degree of vanadium metal preservation (87%) is achieved by preliminary alloying of cast iron to a total concentration of silicon and manganese of at least 2% O and overheating of the metal to the bottom of the blowdown up to 160 ° - 18OO C followed by the introduction of solid vanadium iron and carbon ferromanganese into the converter. This complicates the smelting process. In addition, this method cannot be used to smelt high-quality metal, pure in phosphorus and sulfur content, from the usual vanadium-containing 4yryHia, l content in which (|) spher (O, O5 - 0.06%) and sulfur (0.022 O, O4O%) requires refining from these impurities. The aim of the invention is to improve the quality of the metal and reduce its cost by reducing the loss of vanadium with sclac. The delivered del is achieved by the fact that according to the method of obtaining natural vanadium steel, which includes pouring vanadium chuguts, blowing it with oxidizing gas, deoxidizing and doping the metal in KOHBepTepei before casting iron into the converter,

lime until basicity of slag (% fgQ) is in the range of 1.5-2.5, and purging is carried out with oxygen from the bottom in the temperature range of the melt 1330 - until the carbon content in me is obtained - s tall 0.3-0.9%,

The beginning of the purging of smelting with oxygen at a cast iron temperature of 13 DL and more, compared to the low consumption of lime required for obtaining basic slag (10 1.5–2.5 when the silicon content in the van’s cast iron is 0.2O - 0.30% (typical for pig iron cast iron at the present time), hot start is achieved and intensive development of decarburization, thereby significantly slowing down the oxidation of vanadium. When the temperature of the iron decreases, the effect of carbon is significantly reduced by slowing down the carbon effect .20

The maximum oxidation rate of carbon in the purge process is achieved in the range of carbon concentrations in metal O, 3– 1.3%, which creates the most favorable conditions for the recovery of 25 compressed iron and vanadium from slag to metal during this period. Reduction the carbon content in the metal less reduces the rate of its oxidation and increases the content of iron oxides jg in the slag, facilitating the transition of vanadium from

metal to slag.

Intensive recovery of oxidation and heat in the initial period of smelting j of vanadium from slag to metal during the period of maximum decarburization, ensuring that vanadium concentrations in the steel are 80– 90% of the original in cast iron, is achieved by necessarily fulfilling 40 different conditions — ocHoiBHoctii. slag at the level of 1.5-2.5%. When the atom, the degree of d & phosphorus of the metal is at the required level, due to the specific features of the blowing of vanadium s pig iron with an increased content of vanadium and iron oxides at the beginning of the blowing, which promotes accelerated dissolution of lime in the slag melt and, therefore, oxidation of phosphorus.

 . .. 5i

The found upper limit of the temperature of the metal after purging is limited — due to a sharp decrease in the durability of the lining and the bottom of the converter when higher temperatures are obtained. For 55 cooling and adjusting the heat balance of smelting, steel scrap and hard cast iron are produced.

Example 1. Vanadium cast iron composition,%: C 4, 53; Cr Oh, Yu; M & e, 27; ei0.30; Ti O, 25; Wo, O28; Р О, 05 is poured in the amount of 22 tons to the converter at. The gold is set in an empty converter before casting iron. Lime consumption 19 kg / t. Blowing is carried out with oxygen from below in the shell of natural gas to produce finished steel. Consumption Oxygen 2 -3.4 m / t-min, natural, gas - O, ZO - 0.34. min

The composition of the steel,%: C 0.32; V 0.47} cy-0.09; Ti 0, O2gMiO, 17 {P O, O26; S 0.020. The temperature of the metal at the release. The composition of the final slag,%: CaO 39.1; 510,21,2; M (j.O 5.6 Mio 4.5; Fee 5, l; V / 2.% 3.6; TiQ 12, l; Qsp 0.5;, 5; 60.09. Basicity

slag () 2.11. 5i o 2.

The degree of retention of vanadium in steel is 89%.

Example 2. Vanadium cast iron composition,%: C 4,5; V0.49; Cr O, 14; Mi 0.25; SiO, 25; Ti O, 18; 5 O, 028; P 0, O5, is poured in the amount of 22 tons of bottom converter to blow at 1350t. they sit down in an empty converter to cast iron in an amount of 15 kg / t. Blowing is carried out by oxygen from below in the shell of natural gas with an intensity of 3.7–4.0 m / t-min. The flow rate of natural gas is 10% of the consumption of sour gas.

The composition of the steel,%: C 0,89; VO, 45; Cr 0.13; Mie 0.14; T, 0, B1; P 0.028; 60.024. The temperature of the steel on release. The composition of the final slag,%: CaO 38.6; 9102.21.8; MoO 4.8 Mio 5.4; Fe04, 9; Ti, 0; 0.6; 1.7; -50.08. Basis slag 1.97.

. The degree of preservation of vanadium in steel is 92%.

PRI m e R 3. Vanadium cast iron composition,%: C 4,6; V0.30; , 12; MI 0.34; 5iO, 52; T4 0.14; 50.026; P 0.06, obtained by mixing in a mixer with ordinary vanadium iron with a pig iron, is poured in an amount of 22 tons into the converter of the bottom blown at Lime prisazuyut in an empty converter before pouring iron. Lime consumption Zo kg / t. Purging is carried out with oxygen with an intensity of 3.4–3.7 min. Natural gas consumption is 0.34–0.37 m / /.t min.

The composition of the metal after purging,%: 0.45 iVO, 27; CvO, ld; Mv 0.18;

PM O.OljP 0, O25; SO, 020. Metal temperature 164СРС. The composition of the final slag. %: CaO 46.2; 9iug 24, 2; M & e 4, 4; .

or-ip 0.71 Pqps 1.1; eo.oa. osns "- s

slag content 2.15. .

The degree of preservation of vanadn c. metal 9O%.

In the examples given, the additive of ferroalloys is made equally in the following sequence: when 1/5 of the ladle is filled, ferrochrome is applied, then silica margined evenly until the 3/4 of the ladle is filled. Consumption fe1fohroma brand FH kg / t. Consumption of USW- (5 mangans maxi kg / t. Composition of finished steel (5OHGF),%: C 0.49; VO, 25; SG 1.06; Mri O, 91 J Ti 0.01; P p, O26; SO. pgSi SiO.lS.

With the economic effect of 20 introducing the proposed method by reducing the consumption of ferroalloys will be about 2 rubles. per ton of vanadium containing steel ..

Claims (2)

1. Author's certificate of the USSR N9 453428, cl. C 21 C 5/28, 1971. 2. USSR author's certificate number 6O2557, cl. C 21 C 5/28. 1976.