CN101525678A

CN101525678A - Method of replacing lime with limestone for slagging and producing steel in oxygen top blown converter

Info

Publication number: CN101525678A
Application number: CN200910082071A
Authority: CN
Inventors: 李宏; 曲英
Original assignee: University of Science and Technology Beijing USTB
Current assignee: University of Science and Technology Beijing USTB
Priority date: 2009-04-21
Filing date: 2009-04-21
Publication date: 2009-09-09
Anticipated expiration: 2029-04-21
Also published as: CN101525678B

Abstract

The present invention belongs to the field of steel production, and relates to a method of replacing lime with limestone for slagging and producing steel in an oxygen top blown converter. The invention is characterized in that the limestone is directly added during slagging in the steel production process. The added batch number is increased and the amount of each batch of material is reduced. Namely the lime is added by 1-3 times for slagging formerly, and when the limestone is added for slagging, the limestone is added by 4-8 times. The adding amount of each time, calculated according to the CaO therein, is 1/2-1/3 of lime added formerly and is for preventing the condensing and incrusting at the metal surface in the furnace in the early period of converting. The adding amount of limestone, calculated according to CaO therein, accounts for 30%-100% of adding amount of lime in the batch. The method of the invention has the main advantages of elimination of lime calcining procedure or reduction of production scale, reduction of cost required for operating the calcining device and reducing the discharged pollution, prevention of heat waste caused by cooling the lime after calcining, low sulfur content in the lime generated in the oxygen top blown converter, and benefit for restraining resulfurization of melted iron in the steel production process.

Description

A kind of method of in top-blown oxygen converter, using replacing lime with limestone for slagging and producing steel

Technical field

The invention belongs to the converter steelmaking field, relate to a kind of method of in top-blown oxygen converter, using replacing lime with limestone for slagging and producing steel.

Background technology

Oxygen top blown converter steel making is a process of forcing impurity element in oxygen supply, the rapid oxidation removal molten iron, leaning on elemental oxygen heat-transmission heating molten steel raising temperature, needs to add the lime slag making in stove, to remove the impurity element phosphorus in the molten iron.

Lime is the product that is formed through calcining by Wingdale, generally will be heated to Wingdale more than 1200 ℃ in the production, and calcination process carries out a few hours, and Wingdale (lime carbonate) decomposes therebetween, effusion CO ₂And become lime (calcium oxide).After burning till and come out of the stove, carrying by lime a large amount of physics heat, cool to the temperature that is suitable for transporting and just can transport steelworks to, it absorbs a large amount of heat again and is elevated to temperature of reaction again and lime is joined in the top-blown oxygen converter back, the final bits that generate are consistent with liquid steel temperature, about about 1600 ℃.This shows that with respect to also will reheat intensification in oxygen top-blown converter, a large amount of physical thermal that the lime that calcining generates has has wasted.

Why in oxygen top blown converter steel making, only add lime and do not add lime stone, not record in the steel-making document in past, logical supposition is, at the beginning of the invention of basic bessemer converter method for making steel and between last 100 years afterwards, fed oxygen from air is adopted in pneumatic steelmaking, heat is not rich in the converter, directly add lime stone decomposition in stove and can absorb a lot of heat and the furnace temperature that is difficult to raise, impact is normal smelts and cast, so all be in advance limestone calcination to be become lime, and then join in the converter.But pneumatic steelmaking is adopted after the pure oxygen blowing, the heat that reaction in furnace produces is more than needed for furnace temperature being elevated to tapping temperature, to add steel scrap and pig iron fusing heat absorption toward contact in the converter for this reason, to consume this part heat, its addition can reach 30% of whole amounts of metal at most, and when blowing when the later stage, furnace temperature was too high, also in stove, add lime stone or dolomite absorbing and cooling temperature.Therefore can think that the problem that originally restriction directly adds the furnace heat deficiency of lime stone has not existed, and considers from the angle of energy-saving and emission-reduction, can directly add slagging with Lime stone when oxygen top blown converter steel making.

Summary of the invention

Main purpose of the present invention is directly to add lime stone in the oxygen top blown converter steel making process, cancel the lime calcining operation or reduce the lime production scale, reduce the operation of lime calcining equipment and administer the required expense of pollution, avoid calcining the heat waste that rear lime cooling causes.

A kind of method that in top-blown oxygen converter, adds replacing lime with limestone for slagging and producing steel, directly add Wingdale when it is characterized in that in steelmaking process slag making desiliconization, dephosphorization, and do not add or add less lime, the adding lot number of original oxygen top blown converter steel making process neutral and alkali slag former is increased, reduce the adding quantity of every batch of material; The slag making of promptly original adding lime, generally lime is divided into 1-3 adding, when adding the Wingdale slag making, to be divided into 4-8 adding to Wingdale, each add-on is calculated according to CaO wherein, 1/2-1/3 during for adding lime is to avoid at top-blown oxygen converter blowing initial stage stove inner metal surface condensation crust; The adding total amount of Wingdale is calculated according to wherein CaO, account for this heat lime add total amount 30% to 100% between; In fusion process, should reduce the adding of other cold iron source raw materials in addition.This is the maximum difference that the present invention and original oxygen top-blown converter add lime slagging and producing steel method.

Top-blown oxygen converter adds the replacing lime with limestone for slagging and producing steel method following many advantages:

(1) heats up from joining in the oxygen top-blown converter again after limestone calcination becomes lime, experienced the process of high-temperature heating of high-temperature heating-cooling-again, if lime stone is directly dropped into oxygen top-blown converter, participate in the slagging reaction while calcining, can avoid calcining the heat waste that rear lime cooling causes, only be equivalent to experience first high-temperature heating process, save the energy and reduce discharging CO ₂

(2) therefore can cancel the lime calcining operation or reduce the lime production scale in the iron and steel enterprise, reduce the operation of lime calcining equipment and reduce discharging and pollute required expense;

(3) limestone calcination becomes lime to need a few hours, and can finish in a few minutes in oxygen top-blown converter, and heat utilization efficiency and production efficiency improve, energy savings and cost;

(4) the lime production process has the dust generation to pollute, if in top-blown oxygen converter, calcine under the intensively stirred atmosphere of slag-steel, the lime dust that produces can and participate in reaction in furnace by bits and a molten steel absorption part, and do not have the limestone calcination stove to use the dust that fuel combustion produced, reduce and pollute;

(5) lime stone dinectly bruning in oxygen top-blown converter uses, and the anxiety of the lime moisture absorption in nothing transportation, the process of banking up, carbonating, quality deterioration has reduced the lime inventory carrying cost.

(6) lime stone when calcining because of the inhomogeneous lime product burning that causes easily of being heated, the activity decreased that causes itself and slag to react, and in oxygen top-blown converter, calcining, participating in immediately slagging after the decomposition of limestone reacts, the anxiety of no burning;

(7) lime stone is calcined the byproduct CO that produces in oxygen top-blown converter ₂Can be used as a part of oxygen source of steel-making, reduce the use amount of pure oxygen in the steelmaking process;

(8) fuel of limestone calcination stove use more or less all contains sulphur, lime absorbs sulphur easily and becomes sulfur-bearing lime, in contrast to this, Wingdale is calcined the lime that generates in top-blown oxygen converter can not be infected with these sulphur, therefore the sulphur content in the slag is low after the slagging, and to return sulphur favourable to suppressing the steelmaking process molten iron;

(9) anxiety, sulfur content that the lime that calcining generates in oxygen top-blown converter does not have burning are low, meet the fine fodder principle that present steel industry large-scale production is advocated.

In sum, top-blown oxygen converter adding replacing lime with limestone for slagging and producing steel method will be brought huge environment, economic and social benefit.

Yet, add replacing lime with limestone for slagging and producing steel, will inevitably reduce the steel scrap amount that can melt in the oxygen top-blown converter, and as if melting waste steel can improve output easily, can boost productivity.But from the viewpoint of making the best use of everything, steel scrap is an employed highest source of iron in the STEELMAKING PRODUCTION, with respect to the pig iron and molten iron, pure and contain alloying element, thereby in market in the error-free running period, steel scrap should be high more a lot of than the price of the molten iron and the pig iron, thus in the production process that with the molten iron is raw material, use steel scrap and uneconomical, and preferably adopt non-oxide method melting steel scrap in electric arc furnace to obtain maximum value.In addition, do not add steel scrap and change the adding molten iron into, can produce more heat in the stove, and can not reduce productivity ratio.

Embodiment

Embodiment 1, test are carried out in 25 tons of oxygen top-blown converters.Beginning adds lime stone and fluorite in batches after being blended into 25 tons of rear lower rifle oxygen blast of molten iron temperature raising in 0.5 minute, and lime stone added a collection of 1.2 tons every 1 minute, adds altogether 6 times, and fluorite added once every 2 minutes, was divided into 3 addings.All slag former added about 3 minutes later on, and carbon flame gets up, and enters carbon period.The 12 minutes sampling of falling stove thermometrics of oxygen blast, composition is qualified, and temperature is 1670 ℃, then tapping.

Embodiment 2, test are carried out in 25 tons of oxygen top-blown converters.Add earlier 600 kilograms in lime, add then 2 tons of steel scraps.Be blended into 23 tons of rear lower rifle oxygen blast of molten iron temperature raising in 2 minutes again, begin then to add lime stone and fluorite in batches, lime stone is 1.45 tons in every batch of slag former, adds once every 1.5 minutes, adds altogether 4 times.All slag former added about 2 minutes later on, and carbon flame gets up, and enters carbon period.The 11 minutes sampling of falling stove thermometrics of oxygen blast, composition is qualified, and temperature is 1660 ℃, and tapping then shows that the slag making of adding Wingdale does not influence smelting and normally carries out.

Claims

1, a kind of method of in top-blown oxygen converter, using replacing lime with limestone for slagging and producing steel, directly add Wingdale when it is characterized in that in the oxygen top blown converter steel making process slag making desiliconization, dephosphorization, and do not add or add less lime, the adding lot number of original steelmaking process neutral and alkali slag former is increased, reduce the adding quantity of every batch of material; The slag making of promptly original adding lime, generally lime is divided into 1-3 adding, when adding the Wingdale slag making, to be divided into 4-8 adding to Wingdale, each add-on is calculated according to CaO wherein, 1/2-1/3 during for adding lime is to avoid at top-blown oxygen converter blowing initial stage stove inner metal surface condensation crust; The adding total amount of Wingdale is calculated according to wherein CaO, account for this heat lime add total amount 30% to 100% between.