CN101875995A - Method for deoxidizing and alloying molten steel - Google Patents

Abstract

The invention relates to a method for deoxidizing and alloying molten steel, comprising the following steps of: firstly, measuring the actual oxygen content of each heat of molten steel; then, accurately calculating alloy amount required by deoxidizing and alloying treatment; and conveying alloys with moderate particle size to molten steel of a ladle through a blowing pipe and inert gas to enable ferroalloys to completely melt before floating to the surface of molten steel so as to achieve the deoxidizing and alloying effects almost without loss. In the invention, the alloy amount is accurately calculated, alloys can be sufficiently stirred in molten steel so that the deoxidizing and alloying effects of alloys are obvious, the oxidation loss in the process of deoxidizing and alloying treatment is also avoided, and the quality of molten steel is greatly improved.

Description

Deoxidation of molten steel and alloyage process

Technical field

The present invention relates to the metallurgical technology field, particularly a kind of deoxidation of molten steel and alloyage process.

Background technology

In the smelting process of molten steel, contain a large amount of oxygen in the molten steel, the oxygen percentage composition of molten steel in converter is 400-600 * 10 ^-6If the oxygen percentage composition in the molten steel is not reduced to a certain degree (such as 80-10 * 10 ^-6), will have a strong impact on the quality and the performance of steel, so molten steel must carry out deoxidation and alloying.The alloy that extensively adopts in the existing technology has ferrosilicon, ferromanganese, ferro-aluminum, silico-calcium (iron), silicomanganese (iron), silicon barium (iron), sial (iron) etc.Alloy contains a certain proportion of silicon, manganese, aluminium, silico-calcium element, and these elements are called deoxidant element.At present, generally adopt following formula to calculate deoxidation and the needed alloy amount of alloying:

The alloy amount that adds=(existing alloy amount in the target content-molten steel of alloy in molten steel) * tap/deoxidant element percentage amounts % * yield of alloy %.

In the existing technology, adopt following method to add alloy: when molten steel when smelting furnace is tapped the ladle, molten steel goes out by 1/4 o'clock to begin to add, and goes out by 3/4 o'clock to add.Add slag retaining cap, slag-blocking ball pushing off the slag in the tapping process, to avoid down slag.Gone out will wrap behind the steel in molten steel carry out Argon and handle, guarantee that argon blowing time is more than 4min.

There are following problem in existing converter tapping deoxidation and alloyage process: at first, alloy addition is roughly estimation just, and it is inaccurate to cause alloy addition to calculate.Secondly, alloy does not join in the molten steel under having the situation of oxidation protection from feed hopper, and most of alloy proportion is far smaller than molten steel proportion, make its swim in molten steel and slag above, oxidized in a large number, cause deoxidation effect bad, yield of alloy is low.

Summary of the invention

The purpose of this invention is to provide a kind of effective deoxidation and alloyage process, make it carry out accurate calculation, simultaneously, effectively improve the adding method that improves alloy, improve recovery rate, improve the molten steel quality, reduce production costs the required reductor of molten steel.

Purpose of the present invention is realized by following technical scheme:

In Iron and Steel Production, deoxidation of molten steel and alloying are inseparable.An alloy part that adds in the molten steel plays desoxydatoin, has consumed in deoxidation process, is converted into deoxidation products and is excluded, and remaining part then is retained in the molten steel, plays alloying.So the amount of deoxidant element equals the deoxidant element that deoxidation consumes and adds required deoxidant element amount sum in the finished product molten steel.Actual oxygen content when the present invention will be at the tapping of every stove molten steel accurately calculates respectively deoxidation and the needed alloy of alloying.In the alloy adition process, adopt the winding-up pipe simultaneously, utilize rare gas element that alloy is directly delivered to the ladle bottom.Ladle deoxidation and alloyage process among the present invention may further comprise the steps:

One, calculate alloy addition:

1). when containing a deoxidant element in the alloy, before bessemerizing the tapping that finishes, deliver to ladle by tapping spout to molten steel during, the oxygen percentage composition [%O in analysis by experiment, Determining oxygen probe or other method mensuration molten steel ₁].Simultaneously, calculate oxygen level in the finished product molten steel, the deoxygenation formula is shown in (1), and its equilibrium constant as shown in Equation (2).Under certain condition, the equilibrium constant can be found by steel-making physical chemistry handbook, and the concentration expressed in percentage by weight of finished product molten steel interalloy element is known, utilize formula (2) can calculate with the finished product molten steel in the oxygen percentage composition [%O that balances each other of deoxidant element ₂].

x[M]+y[O]＝M _xO _y (1)

In the formula, M is the deoxidant element in the deoxygenated alloy, and O is an oxygen, and MxOy is the oxide compound that deoxidant element and oxygen generate.X, y are respectively the coefficient of deoxidant element M and O in the equation.

Its equilibrium constant is:

$K_M=\frac{1}{{[\%M_1]}^x{[\%O_2]}^y}---\left(2\right)$

In the formula, K _MBe the equilibrium constant, [%M ₁] be the percentage concentration of deoxidant element in the Finished Steel, [%O ₂] be the percentage composition of the oxygen under the equilibrium conditions.

2), calculate and need in the molten steel to need oxygen percentage composition (the weight) [%O that removes ₃].Method of calculation are seen formula (3),

[％O ₃]＝[％O ₁]-[％O ₂] (3)

3), [%O is sloughed in calculating ₃] percentage composition [%M of the deoxidant element that consumed ₂], method of calculation are seen formula (4),

$[\%M_2]=[\%O_3]\·\frac{x\·a}{y\·16}---\left(4\right)$

In the formula, a is the nucleidic mass of deoxidant element in the alloy.

4), calculate alloy addition:

$W_M=\frac{W_s\&CenterDot;\left(\right[\%{\mathrm{<figure-callout\; id="1"\; label="M"\; filenames="H2009102728703E0000011.png"\; state="\{\{state\}\}">M</figure-callout>}}_1+\%M_2\left]\right)}{\mathrm{\&eta;}}---\left(5\right)$

In the formula: W _MBe alloy addition, W _SBe the molten steel gross weight, η is a deoxidant element weight percent in the alloy.

When two kinds of alloys of employing, when promptly containing deoxidant element A and B respectively in the alloy:

5), calculate the percentage composition that deoxidant element A and B need, simultaneous equation (6) and (7) can obtain the percentage composition (weight) that deoxidant element A and deoxidant element B need add in the alloy.Formula (6) is consulted definite by A, B alloy complex deoxidization state diagram.

[％A]＝k[％B] (6)

$[\%A]\&CenterDot;\frac{y_A\&CenterDot;16}{x_A\&CenterDot;a}+[\%B]\&CenterDot;\frac{y_B\&CenterDot;16}{x_B\&CenterDot;b}=[\%O_1]-[\%O_2]---\left(7\right)$

In the formula, [%A] and [%B] is respectively the percentage composition (weight) that deoxidant element A and deoxidant element B need add, and K is a coefficient, can consult and obtain by A, B alloy complex deoxidization state diagram.[%O ₁] and [%O ₂] be respectively the oxygen percentage composition (weight) tapping back measured and the oxygen percentage composition (weight) in the finished product molten steel.

y _AAnd x _ABe respectively the coefficient of oxygen and deoxidant element A in the chemical equation of deoxidant element A and oxygen;

A is the nucleidic mass of deoxidant element A.y _BAnd x _BBe respectively the coefficient of oxygen and deoxidant element B in the chemical equation of deoxidant element B and oxygen; B is the nucleidic mass of deoxidant element B.

6), calculate alloy addition: the alloy addition that contains deoxidant element A can calculate by following formula:

$W_A=\frac{W_s\&CenterDot;\left(\right[\%A\left]\right)}{\mathrm{\&eta;}}---\left(8\right)$

In the formula: W _ABe the add-on of the alloy that contains deoxidant element A, W _SBe the molten steel gross weight, η is the weight percent of deoxidant element A in the alloy.

In like manner, with percentage composition and η substitution (8) formula of deoxidant element B, can calculate the alloy addition that contains deoxidant element B.The two calculation result addition is total alloy addition.

Two, iron alloy is joined in the ladle by the winding-up pipe: when the molten steel tapping finishes, deoxidation and the needed iron alloy of alloying that aforementioned calculation is obtained directly join in the ladle by inserting the winding-up pipe, feed rare gas element by the winding-up pipe simultaneously, iron alloy is blown to the ladle bottom top.

Above-mentioned iron alloy density can melt before the emersion liquid steel level in order to guarantee the iron alloy of sending into the ladle bottom fully much smaller than molten steel, and the iron alloy granularity should be between 5mm-10mm.

Employing pushing off the slag tapping; for the molten steel surface that adequately protects is not subjected to atmospheric oxidation, in order to protect the iron alloy that partly floats to liquid steel level not oxidized, add covering slag simultaneously on the ladle surface; covering slag thickness is 50mm-100mm, and the charring rice husk that can adopt human configuration is as covering slag.

The winding-up pipe of described insertion, its lower port is 200mm-350mm apart from the distance of ladle bottom.

The rare gas element of described feeding is an argon gas, and jetting pressure is 1.0MPa-1.2MPa.

Beneficial effect of the present invention: deoxidation among the present invention and alloyage process will greatly improve the accuracy of iron alloy add-on, avoided the iron alloy scaling loss, improved the iron alloy recovery rate, recovery rate 5%-8% can be improved than existing deoxidation and alloyage process, tangible economic benefit can be obtained.Simultaneously, owing to by rare gas element alloy feed is arrived ladle bottom, molten steel has obtained sufficient stirring, and molten steel component is even, and various inclusion floating are fast, improved steel quality.

Description of drawings

Accompanying drawing is a ladle deoxidation synoptic diagram of the present invention.

Among the figure, the concrete implication of each label is: 1-alloy winding-up pipe; The 2-covering slag; The 3-ladle; The 4-molten steel; The 5-iron alloy; The 6-argon gas.

Embodiment

Below in conjunction with drawings and Examples the present invention is further described:

Specific embodiment: known carbon content 0.1%, 1600 ℃ of tapping temperatures, the ferrosilicon deoxidation, molten steel oxygen level 0.025% during smelting endpoint, siliceous 0.27% in the finished product molten steel, ferrosilicon siliceous 50%.

1, calculates the ferrosilicon add-on

The silicon that deoxidation consumes: 0.013%

Silicon in the finished product molten steel: 0.27%

Deoxidation of molten steel per ton and alloying needed silicon: 0.013%+0.27%=0.283%

The ferrosilicon amount that steel-deoxidizing per ton and alloying should add is 5.66kg

2, converter floating plug or slag-blocking ball tapping, tapping finishes, and the ladle surface adds the ladle covering slag, ton molten steel consumption 1kg～1.5kg.

3, alloy winding-up pipe is inserted ladle, adopt rare gas element (being argon gas herein) to jet, jetting pressure 1.0MPa, the winding-up amount determines according to calculating, when multiple alloy was arranged, according to the deoxidizing capacity size, ascending winding-up successively entered ladle.

4, after the alloy winding-up finishes, continue the winding-up rare gas element about 1 minute, so that inclusion floating, composition is even.

5, the winding-up effect comparison is as follows:

Content tradition deoxidation alloying of the present invention

Alloy addition 5.66kg/T 6.75kg/T

Finished Steel silicone content 0.27% 0.271%

Yield of alloy is more than 95% 80%

As seen, effect of the present invention is better than the effect of prior art.

Claims (5)

1. deoxidation of molten steel and alloyage process, it is characterized in that: processing step comprises: one, calculate alloy addition:

1). when containing a deoxidant element in the alloy, molten steel is smelted the tapping that finishes, and analysis by experiment, Determining oxygen probe or other method can determine the weight percentage [%O of the oxygen in the molten steel ₁]; Simultaneously, according to following deoxygenation formula (1) and equilibrium constant formula (2), can calculate with the finished product molten steel in the weight percentage [%O of the oxygen that balances each other of deoxidant element ₂];

x[M]+y[O]＝M _xO _y (1)

In the formula, M is the deoxidant element in the deoxygenated alloy, and O is an oxygen, and MxOy is the oxide compound that deoxidant element and oxygen generate; X, y are respectively the coefficient of deoxidant element M and O in the formula;

Its equilibrium constant is:

$K_M=\frac{1}{{[\%M_1]}^x{[\%O_2]}^y}---\left(2\right)$

In the formula, K _MBe the equilibrium constant, [%M ₁] be the concentration expressed in percentage by weight of deoxidant element in the Finished Steel, [%O ₂] be the weight percentage of the oxygen under the equilibrium conditions;

2). calculate the weight percentage [%O that needs the oxygen removed in the molten steel ₃], according to formula (3),

[％O ₃]＝[％O ₁]-[％O ₂] (3)

3). calculate and slough [%O ₃] weight percentage [%M of the deoxidant element that consumed ₂], according to formula (4),

$[\%M_2]=[\%O_3]\&CenterDot;\frac{x\&CenterDot;a}{y\&CenterDot;16}---\left(4\right)$

In the formula, a is the nucleidic mass of deoxidant element in the alloy;

4). calculate alloy addition:

$W_M=\frac{W_s\&CenterDot;\left(\right[\%M_1+\%M_2\left]\right)}{\mathrm{\&eta;}}---\left(5\right)$

In the formula, W _MBe alloy addition, W _SBe the molten steel gross weight, η is a deoxidant element weight percent in the alloy;

5). when adopting two kinds of alloys, be when containing deoxidant element A and B respectively in the alloy, calculate the weight percentage that deoxidant element A and B need respectively, simultaneous equation (6) and (7) can obtain the weight percentage that deoxidant element A and deoxidant element B need add in the alloy; Formula (6) is consulted definite by A, B alloy complex deoxidization state diagram;

[％A]＝k[％B] (6)

$[\%A]\&CenterDot;\frac{y_A\&CenterDot;16}{x_A\&CenterDot;a}+[\%B]\&CenterDot;\frac{y_B\&CenterDot;16}{x_B\&CenterDot;b}=[\%O_1]-[\%O_2]---\left(7\right)$

In the formula, [%A] and [%B] is respectively the weight percentage that deoxidant element A and deoxidant element B need add, and K is a coefficient, can consult and obtain [%O by A, B alloy complex deoxidization state diagram ₁] and [%O ₂] be respectively the oxygen weight percentage tapping back measured and the oxygen weight percentage in the finished product molten steel;

y _AAnd x _ABe respectively the coefficient of oxygen and deoxidant element A in the chemical equation of deoxidant element A and oxygen; A is the nucleidic mass of deoxidant element A; y _BAnd x _BBe respectively the coefficient of oxygen and deoxidant element B in the chemical equation of deoxidant element B and oxygen; B is the nucleidic mass of deoxidant element B;

6), calculate alloy addition: the alloy addition that contains deoxidant element A can calculate by following formula:

$W_A=\frac{W_s\&CenterDot;\left(\right[\%A\left]\right)}{\mathrm{\&eta;}}---\left(8\right)$

In the formula, W _ABe the add-on of the alloy that contains deoxidant element A, W _SBe the molten steel gross weight, η is the weight percent of deoxidant element A in the alloy;

In like manner, with percentage composition and η substitution (8) formula of deoxidant element B, can calculate the alloy addition that contains deoxidant element B; The two calculation result addition can be drawn total alloy addition;

Two, iron alloy is joined in the ladle by the winding-up pipe: when the molten steel tapping finishes, deoxidation and the needed iron alloy of alloying that aforementioned calculation is obtained directly join in the ladle by inserting the winding-up pipe, feed rare gas element in the winding-up pipe, iron alloy is delivered to the ladle bottom top.

2. by described deoxidation of molten steel of claim 1 and alloyage process, it is characterized in that: the granularity of above-mentioned iron alloy should be between 5mm-10mm.

3. by described deoxidation of molten steel of claim 1 and alloyage process, it is characterized in that: above-mentioned ladle surface is added with covering slag, and its thickness is 50mm-100mm.

4. by described deoxidation of molten steel of claim 1 and alloyage process, it is characterized in that: the above-mentioned winding-up infratubal port that is inserted in the ladle is 200mm-350mm apart from the distance of ladle bottom.

5. by described deoxidation of molten steel of claim 1 and alloyage process, it is characterized in that: the rare gas element that feeds in the above-mentioned winding-up pipe is an argon gas, and jetting pressure is 1.0MPa-1.2MPa.

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