RU2442827C2 - Method for extraction of vanadium during conversion of naturally doped cast iron - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: the invention relates to metallurgy and to conversion of vanadium-containing cast iron via duplex processing. At the first phase of the conversion the carbonic preproduct and vanadium slag, at the second phase the carbonic preproduct is processed in the second converter to produce steel. During iron devanadation an oxidising-cooling agent is added to the melt, in the form of agglomerate, agglomerate with cinders and/or non-fluxed vanadium-containing pellets. For the total concentration of silicone and titanium in the cast iron up to 0,10 % the amount of oxidising-cooling agent is equal to 40-70 kg/ton of cast iron, whereas for increasing the total concentration of silicone and titanium for every 0,01 % the amount of oxidising-cooling agent is increased by 0,5-1,5 kg/ton of cast iron.

EFFECT: guaranteed good extraction of vanadium in form of slag from cast iron with different chemical composition of cast iron.

2 tbl, 1 ex

Description

The invention relates to ferrous metallurgy, and in particular to methods for the redistribution of vanadium cast iron in two stages to produce vanadium slag and carbon intermediate in the first stage, and steel in the second stage in another converter.

There are various industrial processes used for processing vanadium cast iron by the duplex process, in the first stage of which vanadium slag and a carbon intermediate are obtained. Vanadium, an important alloying element for metallurgy, has low activity and, accordingly, has a weak affinity for oxygen. Its activity is much lower than the activity of carbon. For this reason, the oxidation of vanadium and its transition to slag are possible only at relatively low temperatures before the onset of active carbon oxidation.

Vanadium cast iron contains silicon - up to 0.30%, titanium - up to 0.25%. During the oxidation of these elements, due to their significantly higher activity than that of carbon and vanadium, 945800 and 935500 J of thermal energy are released, respectively [2]. A cooler is introduced to absorb heat and lower the temperature of the metal during cast iron devanadation.

In all described and used methods for cast iron devandation, the following oxidizing agents are used as oxidizing agents: solid cast iron together with scale, scrap metal in an amount of up to 12% of the mass of cast iron both in cold form and heated to 400-700 ° C, scale and / or pellets.

The closest in technical essence and the achieved result to the claimed method is a method for the redistribution of vanadium cast iron by the duplex process, including devanization of cast iron using agglomerate, scale and / or non-fluxed pellets, agglomerate and scale, agglomerate and non-fluxed] as agglomerating agent .

This method provides cast iron devanation. The consumption of oxidizing agent-cooler is determined depending on the silicon content in cast iron. As already noted, the thermal effect of the titanium oxidation reaction is identical to that of silicon oxidation. The titanium content in cast iron at the same silicon content is different. For this reason, the calculation of the amount of coolant-oxidizer, based on the silicon content, does not give stable results on the extraction of vanadium from cast iron to slag. As a result, significant fluctuations are observed in the content of residual vanadium in the carbon intermediate, and, accordingly, the vanadium slagging coefficient.

Thus, the use of scale, and / or agglomerate, and / or non-fluxed vanadium-containing pellets as an oxidizing agent-cooler, depending only on the silicon content in vanadium cast iron, does not provide stable deep extraction of vanadium from cast iron, which is a significant drawback of this method of processing vanadium cast iron.

A known method of redistributing vanadium-containing cast irons by introducing vanadium slag as oxidizing agents for the slag of the mono process and steel slag of the duplex process at the final stage of accumulation of vanadium slag [3]. The disadvantage of this method is the presence of CaO up to 45% in the proposed additives, which will not ensure stable performance by limiting the CaO content in vanadium slag to not more than 3%.

The task of stable extraction of vanadium from cast iron of various chemical composition is achieved by introducing into the melt as an oxidizing agent-cooler

agglomerate of the following composition: iron content 56-66%;

calcium oxide CaO up to 3%,

dross of the following composition: iron content 60-67%;

calcium oxide CaO up to 0.7%,

unfluxed pellets with an iron content of 60-62%;

calcium oxide CaO up to 3%

or mixtures of these materials in an amount depending on the total content of silicon and titanium in cast iron.

The consumption of oxidizing agents-coolers with a total silicon and titanium content of up to 0.10% should be from 40 to 70 kg / t of cast iron. With an increase in the total content of silicon and titanium, the amount of dross and / or pellets introduced increases by 0.5-1.5 kg / t of pig iron for every 0.01% of the sum of titanium and silicon. When a smaller amount of oxidizing agent-cooler is introduced, the temperature conditions for vanadium oxidation will not be provided, and with a larger amount of oxidizing agent-cooler, melt will be supercooled with the impossibility of further processing of the carbon intermediate.

An example of the redistribution of vanadium cast iron by the duplex process:

vanadium cast iron is poured into the converter and its devanadation is carried out by purging with oxidizing gas with the addition of oxidizing agents-coolers in order to obtain a carbon intermediate and vanadium slag. In this case, agglomerate, agglomerate with scale and / or non-fluxed vanadium-containing pellets in an amount depending on the total content of silicon and titanium in cast iron are used as oxidizing agents-coolers:

with a total silicon and titanium content in cast iron up to 0.10%, the amount of oxidizing agent-cooler is 40-70 kg / t of cast iron;

with an increase in the total content of silicon and titanium for every 0.01%, the amount of oxidizing agent-cooler is increased by 0.5-1.5 kg / t of cast iron. Vanadium cast iron was processed, containing,%:

carbon C 4.5-4.8; vanadium V 0.40-0.50; silicon Si 0.04-0.20; titanium Ti 0.07-0.10; Manganese Mn 0.28-0.35; chromium Cr 0.05; Cu 0.01; phosphorus P 0.04; sulfur S 0,022,

having a temperature of 1280-1305 ° C. The oxygen supply during the purge was in the range of 320-350 nm ³ / min.

Data on the results of experimental swimming trunks produced by the proposed technology and comparative swimming trunks by the existing technology are presented in Table 1, and Table 2.

From the presented tables it follows that according to the technology of the proposed method, the vanadium slagging coefficient is 92.4% at 88.8% according to the technology used. An increase in the vanadium slagging coefficient significantly reduces its losses during further processing of the intermediate product, since when the intermediate product is blown onto steel, all the vanadium present in it passes into slag and is sent to the dump.

A comparative analysis of the proposed technical solution and the prototype method shows that the proposed method guarantees the stable quality of commercial vanadium slag, provides an increase in the extraction of vanadium from cast iron to slag, reduces the environmental load, ensures strict execution of orders on steels with a limited content of vanadium.

These advantages of the proposed method for processing vanadium cast iron are achieved taking into account the total content of silicon and titanium in cast iron, which is the main element of the vanadium extraction method claimed in the present application for converter conversion of vanadium cast iron by the duplex process.

An analysis of patents and scientific and technical information has confirmed that the claimed technology is relevant and meets the criteria of “novelty” and “inventive step”, since essential features are not found in the analyzed information sources. The results of experimental testing, shown in table 1 and table 2, prove the industrial applicability of the proposed method.

The proposed parameters were established experimentally during the redistribution of vanadium cast iron in 160-ton converters with upper oxygen blasting to produce vanadium slag and carbon intermediate in the first stage (devanadation), and steel in the second stage in another converter.

Information sources

1. RU 2201968 C2, C21C 5/28, 04/10/2003.

2. V.A. Kudrin, “Theory and Technology of Steel Production,” Mir Publishing House, 2003, p. 74.

3. Patent 2371483 "Method for the processing of vanadium-containing cast irons", priority March 30, 2007.

Extraction of vanadium from cast iron to slag in pilot melts Table 1 No. p / p Si cast iron,% Ti cast% Cooler consumption, t V residual,% V cast iron,% The degree of slagging,% * one 0,07 0.04 9.2 0,03 0.42 92.8 2 0.09 0.10 10.3 0,03 0.43 93.0 3 0.08 0,07 9.7 0,03 0.42 92.8 four 0,07 0.11 9.6 0,03 0.45 93.3 5 0,07 0,07 9.3 0,03 0.43 93.0 6 0.09 0,07 9,4 0,03 0.47 93.6 7 0.06 0.05 9.1 0.04 0.44 90.9 8 0.08 0,07 9.7 0.04 0.43 90.6 9 0.06 0.09 9.7 0.04 0.45 91.1 10 0.09 0.10 10.3 0,03 0.43 93.0 Averages 0,033 92.4 * Note - degree of slagging = (Vchug-Vp / p) / Vchug

The degree of extraction of vanadium from cast iron to slag in comparative smelting table 2 No. p / p Si cast iron,% Scale consumption, t V residual,% V cast iron,% The degree of slagging,% one 0.14 12.0 0,03 0.43 93.0 2 0.08 7.0 0.05 0.42 88.0 3 0.11 8.5 0,07 0.46 84.7 four 0.08 6.8 0.06 0.42 85.7 5 0.14 13,2 0,03 0.44 93.2 6 0.10 9.7 0.04 0.41 90.2 7 0.11 7.0 0,07 0.43 83.7 8 0.13 11.8 0.04 0.42 90,4 9 0,07 7.0 0.09 0.43 79.0 10 0.15 12.1 0,03 0.43 93.0 Averages 0.051 88.8

Claims (1)

A method of redistributing vanadium cast iron with a duplex process, which includes, at the first stage, pouring vanadium cast iron into the converter and de-devolating it by blowing with oxidizing gas with an oxidizing agent-cooler to produce carbon intermediate and vanadium slag, and at the second stage, processing the carbon intermediate in the second converter to obtain steel, characterized in that as the oxidizing agent-cooler use agglomerate, agglomerate with scale and / or unfluxed vanadium-containing pellets in an amount depending on the total content of silicon and titanium in cast iron, while with a total content of silicon and titanium in cast iron up to 0.10%, the amount of oxidizing agent-cooler is 40-70 kg / t of cast iron, and with an increase in the total content of silicon and titanium for every 0, 01% the amount of oxidizing agent-cooler is increased by 0.5-1.5 kg / ton of cast iron.