CN101545017B

CN101545017B - Ladle slag modifying agent

Info

Publication number: CN101545017B
Application number: CN2008100245662A
Authority: CN
Inventors: 唐洪乐; 左康林; 洪建国; 殷胜
Original assignee: Shanghai Meishan Iron and Steel Co Ltd
Current assignee: Shanghai Meishan Iron and Steel Co Ltd
Priority date: 2008-03-26
Filing date: 2008-03-26
Publication date: 2010-12-22
Anticipated expiration: 2028-03-26
Also published as: CN101545017A

Abstract

The invention relates to a modifying agent for modifying ladle top slag, which mainly reduces the percentage of sigma (FeO+MnO) in the ladle top slag, improves purity of molten steel, and solves the technical problems of carburetion, silicon increase and the like existing in a common modifying agent. The invention adopts a technical proposal that the modifying agent for modifying the ladle top slag comprises the following chemical compositions by weight percentage: 61 to 70 percent of CaO, 15 to 28 percent of Al2O3, 3.5 to 7 percent of Al, 6 to 10 percent of CaF2, 1.5 to 5 percent of MgO, less than 3 percent of SiO2, less than or equal to 0.01 percent of C, and less than or equal to 0.3 percent of control moisture.

Description

A kind of ladle dreg modifying agent

Technical field:

The present invention relates to a kind of auxiliary material that is used for smelting iron and steel, particularly a kind of properties-correcting agent that is used for the ladle top slag modification.

Background technology:

Along with user's requirement harsh day by day to steel product quality, inclusion content of steel must be fewer and feweri, granularity also must be more and more littler, this just requires ladle in refining process, the deoxidation products of molten steel will in time float, and converter steelmaking is carried out deoxidation of molten steel at alloys such as tapping adding ferro-aluminum, ferrosilicon, and the ∑ in the slag (FeO+MnO) % generally is greater than 7%, and the deoxidation products in such molten steel is difficult to come-up.In addition along with when cast liquid steel temperature constantly reduce, the solubleness of oxygen descends, oxygen is separated out the back and is generated aluminium sesquioxide with reactive aluminum in the steel, becomes that inclusion generates and the important source of nozzle clogging, when situation is serious, makes production be difficult to carry out.

At present domestic had material modified, as: a kind of deoxidizing slag-forming agent for ladle furnace, the composition that it is characterized in that deoxidizing slag-forming agent adopts aluminum shot, carbon dust, carborundum powder, silico-calcium barium powder, other materials, the consisting of of each component (following be weight part): 15～35 parts of aluminum shots; 10～40 parts of carbon dusts; 15～40 parts of carborundum powders; 15～35 parts in silico-calcium barium powder; 5～15 parts of other materials, its characteristics are that deoxidation is rapid, and submerged arc speed is fast, have labour intensity low, can improve Working environment, and low characteristics of cost.

At present, wish that ∑ (FeO+MnO) % in the ladle top slag is reduced to less than 5%, and do not have carburetting, increase problem such as silicon for improving the purity of molten steel.

Summary of the invention: the purpose of this invention is to provide a kind of properties-correcting agent that is used for the ladle top slag modification, mainly reduce ∑ in the ladle top slag (FeO+MnO) %, improve the purity of molten steel, solve common properties-correcting agent simultaneously and have carburetting, increase technical problem such as silicon.Technical scheme of the present invention is: a kind of properties-correcting agent that is used for the ladle top slag modification, and the weight percent of its chemical composition is: CaO:57～70%; Al ₂O ₃: 15～28%; Al:3.5～7%; CaF ₂: 6～10%; MgO:1.5～5%; SiO ₂:＜3%; C≤0.01%; Control moisture≤0.3%.

CaO is a requisite composition such as slag making, modification in the STEELMAKING PRODUCTION in this slag system, increases its content and also helps to improve basicity of slag, also helps the slag system deoxidation.In order to guarantee good deoxidation effect, requiring has higher free CaO content in the refining slag, but in the slag during CaO too high levels, slag viscosity increases with CaO content, and this not only influences the mass transfer velocity of sweetening process, and when viscosity is increased to certain value, may cause slag the crust phenomenon to occur, the severe exacerbation desulfurization condition, thus, this slag system is controlled at 57～70% with CaO content; SiO in the synthetic slag ₂Si content in the molten steel is had remarkably influenced, and this slag system requires not increase silicon, so this slag system SiO ₂Control to less than 3%; Al in the slag system ₂O ₃Can adjust the slag system fusing point, with Al ₂O ₃Increase, the viscosity of slag will increase, and its content can be obtained slag making effect preferably in 15～28% scopes; For preventing the ladle dry slag, in the slag system with addition of a spot of CaF ₂Reduce the dry slag degree, CaF ₂Composition Control is in 6～10%; MgO in the modification slag is mainly derived from slag charge and refractory materials, and from the thermodynamics angle, MgO also can provide O ^2-Ion, its sweetening power be a little less than CaO, it is generally acknowledged MgO in the slag＜10% o'clock, the slag system sweetening power is higher, when MgO＞15%, a large amount of MgO can significantly improve slag viscosity, worsens the dynamic conditions of desulfurization, slag desulfurization capacity is descended, but the existence of MgO is useful for the life-span that prolongs refractory materials, therefore, and in the external refining process, should keep certain MgO content in the slag, this slag system is controlled at 1.5～5%.

This synthetic slag experimental technique is: the formulation of 1 slag charge operating procedure:

(1) the every stove of carbon aluminium-killed steel convertor deacidification heat adds 600 kilograms of ladle dreg modifying agents, at tapping oxygen≤500PPm, adds 50 kilograms of ladle slag promotor (the every increase of tapping oxygen 50PPm adds 10 kilograms).

(2) adding opportunity: treat after tapping process adds reductor and alloy, to add the modification slag as early as possible, add fashionable attention and add speed, anti-this adds the obstruction of hand-hole, adding under the nonclogging situation of hand-hole, The faster the better for adding speed, and synthetic slag adds before being controlled at tapping 4/5.

Operating procedure behind 2 converters and the stove

(1) use cleaning turnover ladle, guaranteeing does not have residue in the ladle;

(2) guarantee the red packet tapping, baking temperature of steel ladle must not be lower than 1000 ℃ during tapping;

(3) strengthen tap hole and safeguard, the pushing off the slag operation is carried out in strictness, and control is the quantity of slag＜60mm down;

(4) strengthen slag in the tapping process and stir, the omnidistance BOTTOM ARGON BLOWING of tapping process is strengthened the reaction of slag steel;

By this method, the process data of test sees Table one.

Table one: the partial data of commerical test

The test heat	ΔC(％)	Δsi (％)	Go out argon station FeO+MnO%
				1	0.001	0.002	1.2
2	-0.001	0.006	3.2
				3	-0.002	0.001	3.8
4	0.007	0.006	2.5
				5	0.001	0.002	3.0
Average	0.0012	0.0034	2.74

The invention has the beneficial effects as follows that test shows: in the converter tapping process, add an amount of properties-correcting agent of the present invention, FeO+MnO% average out to 2.74% reaches modified effect when going out the argon station.The process of the test carbon increasing amount, to increase the silicon amount lower, and carbon increasing amount and increase the silicon amount all less than 0.01% reaches carburetting, increases the test requirements document of silicon.

Embodiment:

Properties-correcting agent is made up of quickened lime, pre-melted slag, fluorite, aluminum shot, and its weight percent consists of: quickened lime 42～55%, pre-melted slag 20～40%, fluorite 6～10%, aluminium bits 3～8%.The technical requirements of each component is as follows:

Lime: CaO ≮ 92%, P ≯ 0.04%, S ≯ 0.04%, lime kiln discharge must be prepared burden and finished packing the same day, arrived to use producer to be no more than three days from the kiln discharge to the deliver goods, reached the spot when using, and activity of lime is not less than 350ml.

Fluorite: CaF ₂≮ 90%, SiO ₂≯ 3%.

Al grain: Al＞98%, granularity is less than 20mm.

Pre-melted slag: the pre-melted slag principal constituent is the (CaO-Al of calcium aluminate system ₂O ₃), for guaranteeing purity and homogeneity, production method must adopt the electric smelting method to produce, and the pre-melted slag granularity requirements of producing is less than 35mm.Pre-melted slag Composition Control scope and other performance index require to see the following form two.

Table two: the chemical ingredients of pre-melted slag

CaO	Al ₂O ₃	SiO ₂	MgO	C
					49-54	40-45	＜3.5	5-10	＜0.1

The preparation of properties-correcting agent is the mechanical stirring mixing routinely, and control moisture≤0.3%.

The example that this synthetic slag is implemented sees Table three.

Table three: synthetic slag proportioning example table

	Quickened lime	Pre-melted slag	Fluorite	The aluminium bits
					The present invention	42～55％	32～40％	?7～10％	3～8％
Embodiment 1	55	32	?10	3
					Embodiment 2	50	39	?8	3
Embodiment 3	45	40	?7	8
					Embodiment 4	44	38	?10	8
Embodiment 5	42	40	?10	8

The chemical ingredients of the properties-correcting agent correspondence that obtains sees Table four.

Table four: the chemical ingredients of properties-correcting agent correspondence

CaO

Al ₂O ₃

Al

?CaF ₂

SiO ₂

MgO

C(≤)

Composition

61～70％

15～28％

3.5～7％

?6～10％

＜3％

1.5～5％

0.01％

Example 1

61

28

3.5

?6

＜3％

1.5

0.01％

Example 2

63

20

5.5

?8

＜3％

3.5

0.01％

Example 3

65

18

5.5

?7

＜3％

4.5

0.01％

Example 4

67

15

7

?6

＜3％

5

0.01％

Example 5

70

15

3.5

?10

＜3％

1.5

0.01％

This finished product adopts the double-layer plastic packing, and concrete packing specifications requires to carry out by on-the-spot reinforced required standard, and the suggestion products production is no more than 5 days to using.

Claims

1. properties-correcting agent that is used for the ladle top slag modification, the weight percent of its chemical composition is: CaO:57～70%; Al ₂O ₃: 15～28%; Al:3.5～7%; CaF ₂: 6～10%; MgO:1.5～5%; SiO ₂:＜3%; C≤0.01%; Control moisture≤0.3%.