CN1088112C

CN1088112C - Flux and process for forming slag of converter

Info

Publication number: CN1088112C
Application number: CN99113322A
Authority: CN
Inventors: 孟劲松; 接宏伟; 夏顶忠; 赵雷; 王荣
Original assignee: Angang Steel Co Ltd
Current assignee: Angang Steel Co Ltd
Priority date: 1999-10-08
Filing date: 1999-10-08
Publication date: 2002-07-24
Anticipated expiration: 2019-10-08
Also published as: CN1291657A

Abstract

The present invention provides converter slagging flux and a slagging technique which uses the flux. The flux comprises bauxite which is composed of the following components by weight: at least 45% of Al2O3, at most 30% of SiO2, 7 to 18% of Fe2O3 and impurities, such as CaO, MgO, TiO2P, S, etc. as the rest. The granularity of the bauxite is from 5mm to 30mm. The consumption quantity depends on the variety of steel making and the content of silicon in molten iron, and the consumption range of bauxite for each ton of steel is from 1.6Kg to 9kg. The slagging technique comprises the procedures that slagging material of a first batch and half of bauxite with a specified amount are added at the beginning; the rest bauxite is added when material of a second batch is added. The flux and the slagging technique thereof are favorable to slugging and the prolongation of the service life of ladles. The present invention has the advantages of high desulfurization efficiency, good furnace protection effect and low cost.

Description

The converter steelmaking slagging process

The invention belongs to the converter steelmaking field, particularly a kind of slagging process that adopts bauxite as fusing assistant.

In the converter steelmaking slagging process, for accelerating the lime fusing, make carrying out smoothly of dephosphorization and desulfurization and blowing operation, need to add a certain amount of fusing assistant, in the production practice of converter steelmaking up to now, fluorite all is unique or topmost fusing assistant.

The fluorite main component is CaF ₂, therefore the low fusing point that also can significantly reduce CaO of its fusing point is widely used as converter fluxing medium.But fluorite has erosion to converter lining.After the slag splashing novel process is implemented in converter,, improved MgO content in the slag, used the fluorite slag undesirable, occurred slag easily and return driedly, be stained with phenomenons such as rifle owing to increased the add-on that contains the MgO material.And fluorite is bigger to spattering the slag blanket etch, is unfavorable for slag splashing.In addition, when using the fluorite slag making, the volatilization of part fluorion is arranged and be dissolved in the dedusting sewage, cause environmental pollution.The fluorite price is higher, is unfavorable for reducing cost.

The objective of the invention is to: a kind of novel converter steelmaking slagging technology is provided, improves the change slag effect and the raising slag splashing effect of converter and reduce the slag making expense.

The objective of the invention is to realize by following technical proposal: the red bauxite that adopts following ingredients is as slag former: Al ₂O ₃〉=45%, SiO ₂≤ 30%, Fe ₂O ₃7～18% surpluses are CaO, MgO, TiO ₂, impurity such as P, S, the granularity of this red bauxite is 5～30mm, the red bauxite usage quantity is 1.6～9Kg/ ton steel.

Al in the red bauxite ₂O ₃And Fe ₂O ₃All be fusing assistant, Al ₂O ₃Can form 3CaOAl with the CaO in the lime ₂O ₃And 12CaO7Al ₂O ₃, the fusing point of these two kinds of materials is respectively 1535 ℃ and 1455 ℃, and therefore, Al2O3 can play the fusing point that reduces CaO, promotes the effect of lime fusion.

Therefore, red bauxite is as fusing assistant, Al wherein ₂O ₃Content is high more good more; SiO ₂Few more good more with the content of other impurity.

Adopt red bauxite to be: to begin the oxygen blown while at following oxygen rifle, add half of first slag making material (quickened lime and light dolomite) and regulation red bauxite amount, i.e. 0.8～4.5kg/ ton steel as the converter slag-making technology of fusing assistant.When beginning to add second batch of material (quickened lime and light dolomite), i.e. blowing proceeds to about half the time, adds the remainder red bauxite.

Add first batch of material when for duration of blast is 180 tons of convertor steelmaking process about 20 minutes, beginning to blow, comprise quickened lime, half red bauxite of light dolomite and specified amount, i.e. 0.8～4.5kg/ ton steel, blowing 9～11 minutes the time, adding the remainder of the second mass products lime and red bauxite, this helps avoid and slag occurs and return dried, just in case it is dried that the generation slag returns, can be by the rifle position being improved 200～800mm promotion slag.

The add-on of red bauxite depends on institute's steelmaking kind and silicon content of hot metal.When molten iron contains Si 〉=0.3%, when blowing soft steel, in getting, lower limit, i.e. 1.6～4kg red bauxite/ton steel is when blowing high carbon steel, in getting, the upper limit, i.e. 6～9kg red bauxite/ton steel.

When molten iron contains Si＜0.3%, the red bauxite add-on is 6～9kg/ ton steel, and the molten iron si content is low, the SiO of generation ₂Few, it is also few to produce heat, and slag is mobile poor, and the fusing assistant add-on should be more.

In 180 tons of converters of certain steel mill, adopt red bauxite to make fusing assistant, when molten iron Si 〉=0.3%, every stove steel adds 0.4～0.8 ton of red bauxite (being equivalent to 23～4.6kg/ ton steel), blows 3～4 minutes, and slag can be changed.Controlling well under the prerequisite of rifle position, converting process do not have substantially return dried, the finishing slag good fluidity, wholeization slag process is better than fluorite.Molten iron contains Si＜0.2% o'clock, changes difficulty of slag ratio, occurs slag in the converting process easily and returns dried phenomenon.The red bauxite add-on will be brought up to 1.1～1.5t (being equivalent to 6～8.3Kg/ ton steel), and is similar when it is changed the slag situation and uses fluorite.

Use red bauxite as fusing assistant, in when falling the stove, can be observed slag and trickle along furnace lining, illustrates that slag and furnace lining wettability are good, and easy and furnace lining bonding helps slag splashing.The stove that falls when above-mentioned converter is used fluorite before with the red bauxite test almost be can't see and is spattered slag blanket, after using the red bauxite slag making, the stove that falls almost be can't see backup lining brick, and this explanation has the very complete slag blanket that spatters, reach spattering on the slag blanket and make steel, thereby realize the purpose of slag splashing extending furnace lining life.

A large amount of evidences adopt red bauxite to replace the fluorite slag, have following characteristics:

1. the change slag that helps converting process.

2. can improve the desulfurization degree of converter, desulfurization degree uses 49.4% of red bauxite from using 35% of fluorite to bring up to, and improve 14%, but dephosphorization rate is poor slightly.

3. reduce the slag making cost, the fluorite price is 409 yuan/ton, and the red bauxite price is 120 yuan/ton, can reduce by 1.8 yuan of/ton steel of slag making expense.

4. can significantly improve the slag splashing effect.

5. the fluorine content in the minimizing converter dedusting water reaches the environmental protection standard requirement.

6. can significantly improve ladle life.

Claims

1, a kind of converter steelmaking slagging process is characterized in that using the red bauxite with following composition as fusing assistant: Al ₂O ₃〉=45%, SiO ₂≤ 30%, Fe ₂O ₃7～18%, surplus is CaO, MgO, TiO ₂, impurity such as P, S, the granularity of this red bauxite is 5～30mm, usage quantity is 1.6～9kg red bauxite/ton steel, its technological process is when the blowing of oxygen rifle adds first slag making material quickened lime and light dolomite down, add half of regulation red bauxite amount, i.e. 0.8～4.5kg/ ton steel is to beginning to add second batch of material, i.e. blowing proceeds to a half, adds the remainder red bauxite.

2, converter steelmaking slagging process according to claim 1, it is characterized in that: when 180 tons of total duration of blasts of converter are 20 minutes, begin to blow add first lime and regulation light dolomite in, half of adding bauxite amount, i.e. 0.8～4.5kg red bauxite/ton steel, blowing 9～11 minutes the time, the remainder that adds the second mass products lime and red bauxite, if slag takes place in the converting process afterwards to be returned dried, then 200～800mm, promotion slag are improved in the rifle position.

3, converter steelmaking slagging process according to claim 1 and 2 is characterized in that: when molten iron contained Si 〉=0.3% blowing soft steel, usage quantity was 1.6～4kg red bauxite/ton steel.

4, converter steelmaking slagging process according to claim 1 and 2 is characterized in that: when molten iron contained Si＜0.3% blowing soft steel, usage quantity was 6～9kg red bauxite/ton steel.

5, converter steelmaking slagging process according to claim 1 and 2 is characterized in that: when blowing high carbon steel, usage quantity is 6～9kg red bauxite/ton steel.