CN1300344C

CN1300344C - Converter retaining operation method of preventing splash slag and reducing iron loss

Info

Publication number: CN1300344C
Application number: CNB011110813A
Authority: CN
Inventors: 王虎
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-03-30
Filing date: 2001-03-30
Publication date: 2007-02-14
Anticipated expiration: 2021-03-30
Also published as: CN1377976A

Abstract

The present invention discloses an operation method for converter protection by slag splashing for reducing iron loss in a converter. In the method, a carbon-contained reducing agent, such as powdered coal, coke powder, or graphite powder, etc., is mainly added on the surface of liquid slag in the converter before steel output or in the process of steel output in the converter so as to reduce FeO in the liquid slag, increase the viscosity and the melting point of the slag and achieve the purpose of converter protection by slag splashing. The method which has the advantages of easy application and low cost simplifies the technological operation, obviously reduces the steelmaking cost of the converter and has great economic benefits.

Description

A kind of converter retaining operation method of preventing splash slag that reduces iron loss

Technical field

The present invention relates to a kind of splashing slag in converter technology, be specifically related to a kind of converter retaining operation method of preventing splash slag that reduces iron loss.

Background technology

Spatter stove furnace retaining requirement and accomplish " splashing, glue to such an extent that live, rinse "." splash " is exactly to lack deslagging as far as possible, keeps bits, once hits in smelting and makes an issue of; " sticking as to live " is exactly to guarantee that bits have certain viscosity, control peroxidation steel, and the control end point carbon reduces tapping temperature; " rinsing " is exactly to improve the slag fusing point, reduces iron oxide content, improves basicity and content of magnesia.The raw material that China converter steelmaking factory is used because production product and process system difference are very big, causes terminal point slag composition very inequality.

Influence main component MgO, TFe and the basicity (CaO/SiO of terminal point slag viscosity and fusing point (refractoriness) ₂), basicity and iron oxide content are by raw material and steel grade decision, and wherein the ferric oxide variation range is bigger, fluctuation is in the 10-30% scope, spatter slag blanket enough refractoriness are arranged for making, each factory's popular approach is the MgO content of adjusting in the slag at present, when MgO does not reach certain content, ferric oxide will form the low melting point calcium ferrite with CaO, at this moment to spatter the slag blanket degree of anti-the etch low, do not play the furnace retaining effect, adopt the measure that improves MgO after, FeO in the slag and MgO reaction generate magnesium square iron sand, thereby reduce C ₂The generation of F phase has increased the refractoriness of spattering slag blanket, has obviously improved the effect of slag splashing.According to theoretical analysis and the practice of slag splashing both at home and abroad, in normal converter composition scope, spatter slag blanket enough refractoriness are arranged for making, finishing slag MgO should be controlled in the Table II scope.(subordinate list II)

By Table II as seen, if can reduce finishing slag TFe content effectively, the content of finishing slag MgO is also corresponding controlled, need not adjust too high.Because FeO content is wayward in the steelmaking process, therefore, steel mill relies on adjustment finishing slag MgO that slag is become sticky both at home and abroad at present.However, because the steel grade of smelting is many, the passive scope of terminal point composition is big, and after the technology that adopts slag splashing, only Baosteel still has the MgO content of 7% heat terminal point slag not reach capacity, and directly has influence on the effect of slag splashing.

At present, adopt the operational method of slag splashing both at home and abroad: a kind of is in smelting early stage or process, add calcined magnesite ball and light dolomite (or wagnerite), it is sticking that smelting endpoint is done slag, converter finishing slag MgO content can satisfy the requirement of spattering the slag blanket refractoriness, when the superheating temperature of slag is not high, after the tapping directly nitrogen-blow spatter slag operation; Another kind method be after tapping in the slag MgO content do not reach and spatter the desired numerical value of slag blanket, need to add slag supplying agent and improve MgO content in the slag, when making bits reach certain viscosity, implement the slag splashing operation, but the difficulty of tapping back residue adjustment is the composition of the quantity of slag and slag is not easy accurate estimation, adds slag charge and is not easy to melt fully.

Above-mentioned two kinds of technologies all have wretched insufficiency: be the disadvantageous effect of balance FeO, and the magnesia material of excessive adding, it is excessive that slag charge consumes, because MgO content is than the traditional technology height in the slag, slag viscosity increases, and from the kinetics angle, what are unfavorable for taking off P, S; Reduce the spreadability of slag on the one hand, increase and blow damage; Make on the other hand that iron loss obviously increases in the slag (subordinate list III), this is because along with slag viscosity improves, and iron shot sedimentation difficulty institute extremely in the slag.As figure (4) is relation between slag viscosity and the metal iron loss.

Summary of the invention

The objective of the invention is to develop a kind of slag charge that neither increases, do not cause steelmaking process slag and finishing slag viscosity too high simultaneously again, cause slag band iron loss and blow to decrease to increase, but can before slag splashing, make slag become sticky, implement again the operational method of slag splashing.

Method of the present invention is such, and behind the converter steelmaking blow off, before tapping or in the tapping process, with spraying machine slag liquid jet surface carbon containing reducer in stove, the slag splashing operation is implemented in tapping after the prereduction slag becomes sticky slag afterwards.

The present invention causes slag by increase MgO content to become sticky, but before tapping, reduces by make the FeO in the slag to slag jet surface reductive agent, thereby reduce C ₂F forms mutually, improves viscosity coefficient of dross and fusing point.By Table II as seen, TFe content descends in the finishing slag, the also corresponding reduction of desired finishing slag MgO saturation value.The converter that the finishing slag ferric oxide is low, the cost of slag splashing is low, also obtains high furnace life easily, thereby has improved the effect of slag splashing.

Description of drawings

Fig. 1: TFe content is to the influence of slag melting temperature.

Fig. 2: TFe content is to the influence of slag viscosity in the slag.

Fig. 3: the deteriorate relation of rate and TFe of slag blanket.

Fig. 4: the relation between metal in the dreg iron level and the slag viscosity.

Specific embodiment

See by Fig. 1, TFe reduces to 12% by 18% in the slag, and the bits temperature of fusion is increased to 1510 ℃ by 1330 ℃, illustrates that TFe reduces, fairly obvious to improving the bits fusing point, thereby improve the damage against corrosion of spattering slag blanket, improve the furnace retaining effect of spattering slag blanket, as seen by (Fig. 3), finishing slag TFe content increases to 15% by 12%, spatter the slag blanket rate of deteriorating and be increased to 15% by 4%, as seen, how important finishing slag TFe content is to spattering slag blanket furnace retaining effect.

As seen from Figure 2, TFe content is fairly obvious to the effect of bits viscosity in the slag.And along with the height difference of TFe content, it is also inequality that temperature appears in viscograph, and both differ 50 ℃.

This shows that the height of TFe is to finishing slag viscosity in the finishing slag, melting temperature and furnace retaining influential effect are fairly obvious, key is how before finishing blowing, do not cause bits sticking excessively, both helped metallurgical reaction, make metal microbead be convenient to sedimentation in slag again simultaneously, reduce in the slag and be with iron loss, and after smelting end, make TFe reduction minimizing in the slag again, bits are glued, be convenient to the slag splashing operation, purpose of the present invention is to provide a kind of method of splashing slag in converter operation just.

Embodiment: 50 tons of converters, stove labour is in mid-term.Not tapping immediately behind the converter blow off, but in stove, add powdered graphite and light dolomite (once adding 1.2 kilograms of carbon/ton steel) earlier, tapping after reaction is finished, tapping is complete to be forbidden to leave residual steel in the stove, because body of heater is in steel-supplying position, it is big that slag is sprawled surface-area, slag blanket is thin, and Graphite Powder 99 evenly blows and penetrates in addition, make that the TFe interfacial area increases greatly in Graphite Powder 99 and the slag, because the Graphite Powder 99 amount that is blown into few (1.2 kilograms of ton steel) makes the slag temperature drop little, this moment, slag viscosity was little simultaneously, (FeO) velocity of diffusion is fast, the CO bubble that produces easily overflows, and therefore, the reaction between C-(FeO) is more abundant, FeO descends significantly in the slag thereby make, and slag becomes sticky rapidly.Through observing slag color and flowability, do not need to add again slag supplying agent, observe furnace lining melting loss situation then, decision is spattered slag to which position emphasis of furnace lining, and converter is shaken to zero-bit, then the oxygen rifle is dropped to predetermined rifle position, after the adjusting nitrogen flow met the rules requirement, the beginning nitrogen blowing was implemented slag splashing.Spatter in the slag process appropriate change rifle position in the hope of spattering the maximum efficiency of the quantity of slag.Fire door sprays little clinker proof, and to spatter the scoriform condition good, prepares to finish to spatter slag, before spattering slag and finishing, suitably reduces the rifle position, further improves and spatter the quantity of slag, finishes to spatter slag, carries rifle, cuts off nitrogen, spatters the slag time to continue 3 minutes approximately.After the grate dross, pour remaining slag into slag ladle, wait for next stove smelting.

Before and after the reduced blast furnace, the variation of slag composition sees Table I.By in the table as seen, the ferric oxide in the slag of reduction front and back reduces significantly.P in the slag ₂O ₅Do not reduce yet.

Composition changes before and after spraying into the reduction of Graphite Powder 99 reductive agent slag before the Table I tapping:

Slag composition: (%)	CaO	SiO ₂	Al ₂O ₃	MnO	TFe	P ₂O ₅
Slag composition: (%)	CaO	SiO ₂	Al ₂O ₃	MnO	TFe	P ₂O ₅	Before the slag reduction	51	15	1.0	2.5	22	1.9
After the slag reduction	54	15	1.3	2.4	12.5	2.0	Before the slag reduction	51	15	1.0	2.5	22	1.9

Technology of the present invention is simple, and device simple does not need the slag composition in the strict control smelting process, is convenient to operation, with low cost, reduce slag supplying agent consumption and iron loss significantly, shorten the empty stove time, the slag temperature drop is little, increase converter and eat the steel scrap ability, the slag melting height improves and spatters slag blanket furnace retaining effect.

Table II finishing slag MgO content (recommendation), %

Finishing slag TFe	8-14	15-22	23-30
Finishing slag TFe	8-14	15-22	23-30	Finishing slag MgO	7-8	9-10	11-13

Table III is spattered slag hearth time and is not spattered slag hearth time magnetic separation tailings MFe content, %

Kind	Tailings-1#	Tailings-2#	3#	4#	On average
Kind	Tailings-1#	Tailings-2#	3#	4#	On average	Do not spatter slag	8.8	5.1	6.25	7.15	6.6
Spatter slag	6.84	12.44	10.33	9.28	9.72	Do not spatter slag	8.8	5.1	6.25	7.15	6.6

Claims

1, a kind of retaining operation method of preventing splash slag that reduces the converter iron loss, it is characterized in that: behind the converter steelmaking blow off, before tapping or in the tapping process, with spraying machine slag liquid jet surface carbon containing reducer in stove, the slag splashing operation was implemented in tapping afterwards after the prereduction slag became sticky slag.

2, a kind of retaining operation method of preventing splash slag as claimed in claim 1, it is characterized in that: not tapping immediately behind the converter blow off, before converter tapping, use spraying machine slag liquid jet surface carbon containing reducer in stove, tap behind the prereduction slag, in stove, add the dry slag agent afterwards, implement the slag splashing operation subsequently.

3, retaining operation method of preventing splash slag according to claim 1 is characterized in that: described reductive agent contains the powder mixture that graphite or coke or coal and light dolomite contain magnesian, emitted dose ton steel 0.5-2 kilogram carbon.