CN101298632A - BaO-containing external slag washing desulfuration refining agent - Google Patents

Abstract

The invention discloses an external desulfurizing and refining agent for the slag cleaning of a furnace containing BaO, belongs to the processing of fused iron alloy, and particularly relates to a processing and refining agent that is added for removing impurity in the liquid steel. The refining agent comprises barium carbonate, lime, bauxite and fluorite, and is characterized in that the compound consists of following components by weight percentage: 10 to 20 percent of BaO, 40 to 50 percent of CaO, 20 to 30 percent of Al2O3, 6 to 11 percent of CaF2, and remaining impurity and caking agent. Compared with the prior art, the external desulfurizing and refining agent has the advantages of good desulfurizing effect, remarkable lowering of sulfur content in the steel and improved steel quality; the refinement and the desulfurization of parts of the steel grades through an LF furnace can be avoided, thus accelerating production speed and being favorable for lowering steelmaking cost; and the refining agent of the invention has safe production, storage and use.

Description

Contain outer " wash heat " desulfuration refining agent of BaO stove

Technical field

The invention belongs to the processing of fusion iron class alloy, relate in particular to and remove the processing refining agent that impurity adds in the molten steel.

Background technology

Sulphur is one of harmful element in the steel, and is often poly-partially at crystal boundary or out-phase interface with the MnS form, seriously reduced the processing characteristics and the use properties of steel.Molten steel is carried out external refining, further reduce sulphur content in the steel,, have crucial meaning improving the quality of products and enlarging range of product.Outer " wash heat " desulfurization of stove is without easy, quick, the cost-effective secondary desulfurization method of LF stove purified, though be specially adapted to not have refining unit such as LF or the very fast converter steel factory of refining unit rhythm of production such as LF is arranged.Adopt outer " wash heat " desulfuration refining agent of a kind of stove now, each compositions in weight percentage is by CaO65～70%, Al ₂O ₃5～10%, CaC ₂7～11%, M _A1＞2% forms.Outer " wash heat " sweetening agent of existing stove mainly is CaO base and CaC ₂Base, the main drawback of its CaO base are that the secondary desulfurization ability is not too strong; Its CaC ₂The base main drawback is that moisture-sensitive lost efficacy in production, storage and use, also has potential safety hazard.

Summary of the invention

In order to overcome the deficiency that prior art exists, the purpose of this invention is to provide outer " wash heat " desulfuration refining agent of a kind of BaO of containing stove, improve outer " wash heat " desulfuration efficiency of stove, production, storage and easy to use, safe.

Contain outer " wash heat " desulfuration refining agent of BaO stove, include barium carbonate, lime, bauxitic clay and fluorite, characteristics are that said composition is made up of following component by weight percentage: BaO10～20%, CaO40～50%, Al ₂O ₃20～30%, CaF ₂6～11%, all the other are impurity and caking agent.

The present invention program further improves: be somebody's turn to do " wash heat " desulfuration refining agent, include barium carbonate, lime, bauxitic clay and fluorite, characteristics are that said composition is made up of following component by weight percentage: BaO10～13%, CaO47～50%, Al ₂O ₃20～30%, CaF ₂6～11%, all the other are impurity and caking agent.

The present invention program further improves: be somebody's turn to do " wash heat " desulfuration refining agent, include barium carbonate, lime, bauxitic clay and fluorite, characteristics are that said composition is made up of following component by weight percentage: BaO14～16%, CaO44～46%, Al ₂O ₃20～30%, CaF ₂6～11%, all the other are impurity and caking agent.

The present invention program further improves: be somebody's turn to do " wash heat " desulfuration refining agent, include barium carbonate, lime, bauxitic clay and fluorite, characteristics are that said composition is made up of following component by weight percentage: BaO17～20%, CaO40～43%, Al ₂O ₃20～30%, CaF ₂6～11%, all the other are impurity and caking agent.

Be explained as follows with regard to the desulphurization mechanism that adds the alternative CaO of part BaO in the CaO base desulfuration refining agent below.

1, desulphurization reaction

As everyone knows, Ba and Ca are the second family metallic elements in the periodic table of elements, and BaO and CaO are the strong basicity oxide compounds, because Ba is the period 6 element, Ca is the period 4 element, so the alkalescence of BaO is stronger than CaO, sweetening power is also strong than CaO.

Desulphurization reaction and the desulphurization reaction free energy relational expression thereof of BaO in molten steel is as follows:

BaO _(s)+[S]+[C]＝BaS _(s)+CO _(g)

ΔG ⁰＝36940-58.98T J/mol

Desulphurization reaction and the desulphurization reaction free energy relational expression thereof of CaO in molten steel is as follows:

CaO _(s)+[S]+[C]＝CaS _(s)+CO _(g)

ΔG ⁰＝92063-69.48T J/mol

Above-mentioned formula is derived out by following formula voluntarily:

[C]+[O]＝CO _(g) ΔG ⁰＝-22394-39.68T J/mol

(see steel-making chart data handbook commonly used, Chen Jiaxiang writes Beijing 1984:574 of metallurgical industry press first version)

CaO _(s)＝Ca _(g)+[O] ΔG ⁰＝671431-197.5T J/mol

Ca _(g)+[S]＝CaS ΔG ⁰＝-556974+161.3T J/mol

(see the desulfurization in the Iron and Steel Production, Zhang Rongsheng writes.Beijing metallurgical industry press.The 1986:49 first version)

BaO _(s)＝Ba _(g)+[O] ΔG ⁰＝580899-169.0T J/mol

Ba _(g)+[S]＝BaS ΔG ⁰＝-521565+149.7T J/mol

(see physical chemistry and steel-making, Qu Ying etc. translate.Beijing metallurgical industry press.The 1984:226 first version)

Further release:

${\[\%S\]}_{\mathrm{Ba}0}={\[\%S\]}_{\mathrm{Cao}}.\exp (1.27-\frac{6631}{T})$

In the formula:

Δ G ⁰: reaction normal gibbs free energy change value

Exp: mathematic sign.Exp{f _(x)Expression e ^{F (x)}

[%S] _BaO: during BaO desulphurization reaction balance, the weight percentage of sulphur in the steel.

[%S] _Cao: during CaO desulphurization reaction balance, the weight percentage of sulphur in the steel.

T: absolute temperature

Hence one can see that, and the BaO desulphurization reaction is big than CaO of the absolute value of free energy negative value not only, and promptly the BaO sweetening power is stronger than CaO, and about the low order of magnitude of [S] content of molecular balance than CaO.

2, the sulphur content distribution coefficient (L that contains the BaO slag system _S) than higher

In CaO base desulfuration refining agent, add BaO, under the situation of (%BaO)/(%CaO)＜1, its sulphur content distribution coefficient L _SBe to increase with BaO content.L _SIncrease the then also corresponding increase of impellent of desulphurization reaction.

(see Li Suqin, polar wind sulphur steel refining slag system sulfur capacity heat balance test research, the Baotou Iron ﹠ Steel Inst journal, 2003.3:225-226)

3. sulphur mass transfer coefficient β in containing the BaO slag system _(s)Bigger, desulfurization rate is higher

With the increase of BaO content, the corresponding reduction of fusing point of CaO base desulfuration refining agent with viscosity.According to stoke--einstein formula carries out revised Sutherland moral formula

$D=\frac{K_{B}T}{4\mathrm{\πR\η}}$

(see the heat and mass phenomenon in the metallurgy.GH Geiger etc.Beijing metallurgical industry press.The 1981:512 first version)

In the formula:

K _B: Boltzmann constant (1.381 * 10 ^-23J/K);

R universal gas constant (8.314J/molK)

When slag viscosity (η) reduction, then diffusion coefficient D just increases.Because mass transfer coefficient β=D/ δ ' (δ ' efficiency frontier layer thickness), so the corresponding increase of β, desulphurization reaction speeds up.

Outer " wash heat " desulfuration refining agent of stove of the present invention prepares at normal temperatures and pressures.The earlier chemical ingredients and the granularity of check raw material then will each qualified raw material be carried out weighing and burden → addings binding agent → be mixed → granulation → oven dry → cooling weighing afterwards by ratio requirement and are packed.

During use by processing requirement once or gradation join in the ladle.

Compared with prior art, its advantage is: sweetening effectiveness is good, and sulphur content significantly descends in the steel, and the quality of steel is improved; The part grade of steel can have been accelerated rhythm of production without LF stove refining desulfuration, helps reducing steel-making cost; Refining agent production of the present invention, storage and safe in utilization.

Embodiment

Embodiment 1:

Earlier raw material is handled Chemical Composition, the granularity of check barium carbonate, lime, bauxitic clay and fluorite; At normal temperatures and pressures each qualified component raw material is carried out weighing and burden → adding binding agent → be mixed → granulation → oven dry → cooling back weighing pack by the weight percent of specified each component of table 1.Result of use desulfurization degree η _s% lists in the table 1.η _sThe % value is big more, and desulfuration efficiency is just high more.

Embodiment 2:

Method according to embodiment 1 is prepared and uses, and the weight percent and the desulfuration efficiency of each component are listed in the table 1.

Embodiment 3

Method according to embodiment 1 is prepared and uses, and the weight percent and the desulfuration efficiency of each component are listed in the table 1

Comparative Examples 1:

Press outer " wash heat " sweetening agent of stove of the weight percent composition of specified each component of table 1, use back average desulfurization degree η _s≤ 25%.

Comparative Examples 2:

Press outer " wash heat " sweetening agent of stove of the weight percent composition of specified each component of table 1, use back average desulfurization degree η _s≤ 27%.

Table 1 wash heat desulfuration refining agent composition, add-on and desulfurization degree contrast table

As can be seen from Table 1, the sweetening effectiveness of outer " wash heat " desulfuration refining agent of the BaO of containing stove of the present invention obviously is better than the desulfuration refining agent of Comparative Examples.

Claims (4)

1, contains outer " wash heat " desulfuration refining agent of BaO stove, include barium carbonate, lime, bauxitic clay and fluorite, it is characterized in that said composition by weight percentage, form by following component: BaO10～20%, CaO40～50%, Al ₂O ₃20～30%, CaF ₂6～11%, all the other are impurity and caking agent.

2, contain outer " wash heat " desulfuration refining agent of BaO stove according to described this of claim 1, it is characterized in that said composition is made up of following component by weight percentage: BaO10～13%, CaO47～50%, Al ₂O ₃20～30%, CaF ₂6～11%, all the other are impurity and caking agent.

3, contain outer " wash heat " desulfuration refining agent of BaO stove according to described this of claim 1, it is characterized in that said composition is made up of following component by weight percentage: BaO14～16%, CaO44～46%, Al ₂O ₃20～30%, CaF ₂6～11%, all the other are impurity and caking agent.

4, contain outer " wash heat " desulfuration refining agent of BaO stove according to described this of claim 1, it is characterized in that said composition is made up of following component by weight percentage: BaO17～20%, CaO40～43%, Al ₂O ₃20～30%, CaF ₂6～11%, all the other are impurity and caking agent.