CN1291657A

CN1291657A - Flux and process for forming slag of converter

Info

Publication number: CN1291657A
Application number: CN 99113322
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: 2001-04-18
Anticipated expiration: 2019-10-08
Also published as: CN1088112C

Abstract

A flux for forming slags of converter is a bauxite containing Al2O3 (greater than 45%), SiO2 (less than 30%), Fe2O3 (7-18%), and impurities including CaO, MgO, TiO2, P and S. Its slag-forming process features that the first part of raw materials is added in conjuction with half of bauxite and the rest of raw materials along with the rest of bauxite are then added. Its advantages include high desulfurizing efficiency and converter protecting effect, low cost and long service life of ladle.

Description

Converter slag-making fluxing agent and slagging process

The invention belongs to the converter steelmaking field, the slagging process of particularly a kind of new flux and this fusing assistant of employing.

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 slag-making fluxing agent is provided and utilizes the slagging process of this fusing assistant, improve the change slag effect of converter and improve the slag splashing effect 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 ℃, therefore, and Al ₂O ₃Can play the fusing point that reduces CaO, promote 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.

For duration of blast is 180 tons of convertor steelmaking process about 20 minutes, add first batch of material when beginning to blow, comprise quickened lime, half red bauxite of light dolomite and specified amount, i.e. 0.8～4.5kg/ ton steel blew 9～11 minutes the time, the remainder that adds the second mass products lime and red bauxite, this help avoid occur slag return dried, just in case take place slag return dried, 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.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 2.3～4.6kg/ 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.Occur slag in the converting process easily and return 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 new flux red bauxite of the present invention 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 converter slag-making fluxing agent is characterized in that the red bauxite that this fusing assistant is made up of following ingredients: 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.

2. converter slag-making fluxing agent according to claim 1 is characterized in that: when molten iron contained Si 〉=0.3% blowing soft steel, usage quantity was 1.6～4kg red bauxite/ton steel.

3. converter slag-making fluxing agent according to claim 1 is characterized in that: when molten iron contained Si＜0.3% blowing soft steel, usage quantity was 6～9kg red bauxite/ton steel.

4. converter slag-making fluxing agent according to claim 1 is characterized in that: when blowing high carbon steel, usage quantity is 6～9kg red bauxite/ton steel.

5. slagging process that uses the described converter slag-making fluxing agent of claim 1, it is characterized in that: when the blowing of oxygen rifle adds first slag making material quickened lime and light dolomite down, add half that stipulate the red bauxite amount, i.e. 0.8～4.5kg/ ton steel; To beginning to add second batch of material, i.e. blowing proceeds to half the time, adds the remainder red bauxite.

6. converter slag-making technology according to claim 5, it is characterized in that: when 180 tons of total duration of blasts of converter are 20 minutes, in half of the amount that adds first lime and regulation of beginning to blow, i.e. 0.8～4.5Kg red bauxite/ton steel, blowing 9～10 minutes the time, adding the remainder of the second mass products lime and red bauxite, returning dried if slag takes place in the converting process afterwards, then 200～800mm, promotion slag are improved in the rifle position.