RU2419658C2 - Iron flux containing vanadium - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: here is disclosed composition of vanadium agglomerate used for melting vanadium iron as vanadium containing iron flux with oxides of iron, calcium, silicon, manganese, vanadium and sulphur. Content of the said components is chosen from the following conditions: V₂O₅/Fe_total>0.005; CaO/SiO₂=3÷9.5; Mn_total=0.2÷2%. Content of sulphur in it does not exceed 0.08 %.

EFFECT: usage of iron flux of disclosed composition facilitates melting vanadium iron of proper quality with lower specific consumption of coke and iron ore materials at raised efficiency of furnace and higher degree of vanadium extraction into iron.

2 cl, 4 tbl, 1 ex

Description

The invention relates to the field of ferrous metallurgy, in particular to the production of blast furnaces of the vanadium-containing pig iron.

A known method of blast furnace smelting of titanium-magnetite raw materials [1], used at the Nizhny Tagil Metallurgical Combine, which consists in the joint smelting of pellets with a basicity of 0.3-0.5, agglomerates and fluxes in the form of crude alkaline earth metal carbonates. The consumption of raw fluxes is 10-12 kg / t of pig iron for every 10% of pellets from the weight of the iron ore charge.

The main disadvantage of this method is the need for additional heat in blast furnace for the decomposition of carbonates, which leads to increased coke consumption and reduced furnace productivity.

This disadvantage is eliminated by using, as a flux, instead of raw carbonates of alkaline earth metals, a highly basic sinter - iron flux.

The known composition of highly basic agglomerate [2], wt.%: SiO ₂ 3-6; CaO 10-30; MgO 2.0-6.5; Al ₂ O ₃ 0.5-1.5; MnO 1-4; FeO 12-18; Fe ₂ O ₃ 45-55.

The disadvantage of this invention is that in the composition of the sinter there are no vanadium compounds and a high manganese content. The use of this agglomerate as a flux for the smelting of vanadium cast iron is unacceptable, since it leads [4] to an insufficient vanadium content and an excessively high manganese content in the metal, which does not provide the proper composition of commercial vanadium slag during further processing.

Closer in technical essence and the achieved result is the composition of the agglomerate shown in paragraph 4 of the claims [3] and which contains, wt.%:

Fe 49-52 Fe ₂ O ₃ 45.3-47.3 FeO 22.9-24.9 SiO ₂ 5.1-7.1 Al ₂ O ₃ 1.8-2.6 CaO 5.8-11.22 MgO 2.2-3.1 V ₂ O ₅ 1.0-1.47 MnO 2.41-2.56 Cr ₂ O ₃ 2.01-2.13 TiO ₂ 2.9-4.1 P ₂ O ₅ 0.04-0.06 FROM 0.42-0.52

The basicity (CaO / SiO ₂ ) of this vanadium agglomerate is declared in the range of 0.7-2.2, and it can be used as vanadium-containing iron flux with basicity values closer to the upper limit. The necessary ratio V ₂ O ₅ / FeO _total is maintained in the agglomerate, but the restriction on the manganese content, with an increased consumption of agglomerate, can lead to substandard cast iron [4].

The main disadvantage of this invention is the relatively low basicity of the agglomerate, which, on the one hand, makes it difficult to use as a flux, and on the other hand, does not fully provide the required metallurgical properties (reducibility, softness, strength) [5, pp. 167-169 ; 6, pp. 143-146]. At low costs of such an agglomerate, raw carbonate fluxes are not completely removed from the blast furnace charge. At high costs of such an agglomerate, its metallurgical properties will have a significant effect on the performance of blast furnace smelting. Another disadvantage of this invention is the lack of requirements for the composition of the material restrictions on the sulfur content, which can also lead to substandard cast iron [4].

The objective of the present invention is to obtain and use in blast furnace instead of raw carbonate fluxes of a highly basic agglomerate - vanadium-containing iron flux, characterized by increased metallurgical properties. This will ensure the smelting of vanadium cast iron of good quality with lower specific consumption of coke and iron ore materials with increased furnace productivity and a higher degree of vanadium extraction into cast iron.

This goal is achieved by the fact that the composition of vanadium-containing iron flux is limited by the following conditions:

V ₂ O ₅ / FeO _total ≥0.005

CaO / SiO ₂ = 3 ÷ 9.5

Mn _total = 0.2 ÷ 2%.

In addition, it is envisaged to limit the sulfur content in the composition of iron flux to not more than 0.08%.

The selected restriction on the ratio of vanadium and iron oxides in iron flux provides the required vanadium content in cast iron.

The selected basicity (CaO / SiO ₂ ) of iron flux, in addition to the complete exclusion of raw limestone from a blast furnace charge at its corresponding costs, forms an agglomerate structure, consisting mainly of single-calcium ferrite, which is the most readily reducible complex iron compound. The advantages of a material consisting of single-calcium ferrite also include high cold and hot strength and a very narrow temperature range of softening [6, p.143-146]. A basicity of more than 3 excludes the presence of brittle glass in the composition of iron flux [5, p.167-168]. A basicity of less than 9.5 limits the formation of hardly refractory dicalcium ferrite in the composition of iron flux [6, p. 144].

The exclusion of carbonate fluxes from the blast furnace mixture has a number of positive aspects, namely: a decrease in the concentration of carbon dioxide in the dry region of the blast furnace, a decrease in the specific yield of blast furnace gases, stabilization of the thermal state of the steam and shoulders. Reducing the concentration of carbon dioxide in the dry area of the blast furnace enhances indirect recovery by shifting the reaction equilibrium

in the forward direction. This reaction, in contrast to the direct reduction reaction, is exothermic. Reducing the specific yield of blast furnace gases reduces the loss of heat and dust. In the presence of limestone in the charge, it in any case comes to the high-temperature zones discretely and locally, which is explained by both its relatively low consumption and the capabilities of the loading devices used. The stabilization of the thermal state of the boil and shoulders (in the absence of carbonates) contributes to a more complete recovery of vanadium and an increase in the coefficient of extraction of vanadium in cast iron. All this also provides an increase in technical and economic indicators of the heat.

The limits of the content of manganese in the iron flux are due to the task, on the one hand, of improving the conditions for desulfurization of pig iron and reducing the carbide formation of titanium, on the other hand, of obtaining conditional commercial vanadium slag from vanadium cast iron [4].

An additional restriction on sulfur content in iron flux minimizes the likelihood of producing substandard cast iron.

The following is an embodiment of the invention that does not exclude other variations within the scope of the claims. In particular, in the sinter charge for producing iron flux, it is possible to use additional scale, iron and vanadium sludges and slags (for example, steel and ferroalloy), ores and concentrates.

An example of a specific implementation.

Vanadium-containing iron flux was obtained during agglomeration by agglomeration. The composition of the sinter mixture included the following components: a mixture of sinter removal and suction dust, blast furnace dust from blast furnaces smelting vanadium cast iron from agglomerated raw materials of the Kachkanarsky deposit, manganese concentrate of the Zhairemsky GOK, limestone, and coke breeze. The average composition of the charge for the production of iron flux is given in table 1.

Table 1 The composition of the sinter mixture No. Component Consumption % kg / t one a mixture of sinter and suction dust 65.3 784 2 blast furnace dust 8.9 107 3 limestone 21,2 255 four manganese concentrate 2.5 thirty 5 coke breeze 2.1 25,2

Sintering of iron flux was carried out on a sinter machine MAK-75. The sintering process of iron flux was characterized by the following average parameters:

- charge moisture content - 6.5-7.0%;

- the height of the charge layer is 290-300 mm;

- vacuum before the exhauster - 873 mm water column;

- sinter speed - 1.36 m / min;

- ignition temperature of the charge - 1053 ° C;

- gas consumption for ignition - 530 m ³ / h (6.6 m ³ / t);

- return share - 15.8%.

The weighted average chemical composition of the obtained iron flux is presented in table.2.

The initial blast furnace charge consisted of pellets (natural basicity ~ 0.3) and fluxed sinter Kachkanarsky GOK, coke, manganese additives, limestone, which corresponds to the charge according to the method [1]. The ratio in the mixture of pellets KGOK and agglomerate KGOK was maintained constant - 60:40. Smelting was carried out on a blast furnace with a volume of 2200 m ³ and included three periods:

period 1 - work according to the method [1];

period 2 - work using the agglomerate of the prototype [3];

period 3 - work using vanadium-containing iron in the batch of iron flux according to the invention (work using the agglomerate according to the patent [2] was not considered, since the calculated vanadium content in cast iron is less than 0.4% with the consumption of this material exceeding 5%).

In the experience of the prototype, as the iron flux and instead of the manganese additive and part of the limestone, the damper vanadium agglomerate of the above composition was used (basicity 2.2).

In the experiment according to the invention, instead of manganese additives and all limestone, vanadium-containing iron flux of the following composition was used, wt.%:

table 2 Fe _commonly CaO SiO ₂ CaO / SiO ₂ V ₂ O ₅ Mn _total V ₂ O ₅ / Fe _total 43.02 25,765 5.58 4.61 0.35 1.00 0.008

The consumption of iron flux (damper vanadium agglomerate) both in the prototype and in the present invention was 10% of the total mass of the ore part of the charge. The independent parameters of blast furnace smelting were unchanged.

During the tests, the quality of cast iron and slag, furnace productivity, coke consumption, blast furnace dust removal, vanadium distribution coefficient between cast iron and slag (L _ν = [V] / (V)), vanadium extraction coefficient (CIV) in cast iron were recorded. The test results are presented in table 3.

Table 3 Blast furnace performance Indicators Periods one 2 3 The content in the mixture,% manganese sinter 0.4 - - limestone 3.8 2 - iron flux (damper agglomerate) - 10 10 Furnace productivity, t / day 5490 5380 5804 Coke consumption, kg / t: 412 400 383 Iron consumption, kg / t 978 970 965 Removal of blast furnace dust, kg / t of cast iron 31 thirty 25 The degree of use of CO without CO ₂ flux,% 48.8 49.2 50.8 The chemical composition of cast iron,%: Si 0.08 0.08 0.08 Mn 0.31 0.34 0.31 S 0.02 0.019 0,020 V 0.42 0.46 0.430 Ti 0.15 0.16 0.15 Slag basicity, units 1.24 1.24 1.24 L _ν ([V] / (V)), units 3,544 3,963 4,513 KIV,% 81.9 82.7 84

The results shown in table 3, clearly show that the use of iron flux vanadium-containing the claimed composition contributes to a significant increase in furnace productivity, lower coke consumption, specific consumption of iron and dust removal, as well as an increase in KIV.

According to the conditions for smelting cast iron, conditional in terms of sulfur content, in industrial conditions, the limit on the sulfur content in vanadium-containing iron flux is estimated to be no more than 0.08% (Table 4).

Table 4 Influence of sulfur content in iron flux at its various consumption on sulfur content in cast iron The content of iron flux in the mixture,% The content of S in iron flux,% [S] 5 0.08 0.018 0.09 0.019 0.1 0.019 10 0.08 0.019 0.09 0,020 0.1 0,022 fifteen 0.08 0.024 0.09 0,026 0.1 0,03 twenty 0.08 0,029 0.09 0,032 0.1 0,035

Analysis of the above results shows that the claimed composition of vanadium-containing iron flux, when using the latter in titanium magnetite blast furnace smelting, provides for the production of vanadium-containing pig iron of proper quality and helps to increase technical and economic indicators of production.

Information sources

1. Patent of Russia No. 2063443, decl. 1993.08.06, publ. in the BI 1996.07.10.

2. Russian Patent No. 2146296, pending. 1999.07.06, publ. in BI 2000.03.10.

3. Russian Patent No. 2124563, filed 1998.01.15, publ. in BI 1999.01.10.

4. The standard of the enterprise is STP 102-12-2005. Vanadium cast iron.

5. Metallurgy of pig iron / ed. Yu.S. Yusfina. - Ed. 3rd, rev. and add. - M.: IKC Akademkniga, 2004.774 p.

6. Leontyev L.I. Pyrometallurgical processing of complex ores. [Text] / Leontyev L.I., Vatolin N.A., Shavrin S.V., Shumakov N.S. // M .: Metallurgy, 1997 .-- 432 p.

Claims (2)

1. Vanadium agglomerate used for the smelting of vanadium iron as a vanadium-containing iron flux containing oxides of iron, calcium, silicon, manganese and vanadium and sulfur, characterized in that the content of these components is selected from the following conditions:
V ₂ O ₅ / Fe _total ≥0.005
CaO / SiO ₂ = 3 ÷ 9.5
Mn _total = 0.2 ÷ 2%. 2. Agglomerate according to claim 1, characterized in that the sulfur content in it does not exceed 0.08%.