CN103352101B

CN103352101B - Low-cost smelting technology of converter

Info

Publication number: CN103352101B
Application number: CN201310248732.8A
Authority: CN
Inventors: 孙风梅; 管挺; 刘飞; 马建超; 程奎生; 皇祝平
Original assignee: Jiangsu Shagang Iron and Steel Research Institute Co Ltd
Current assignee: Jiangsu Shagang Iron and Steel Research Institute Co Ltd
Priority date: 2013-06-21
Filing date: 2013-06-21
Publication date: 2015-07-22
Anticipated expiration: 2033-06-21
Also published as: CN103352101A

Abstract

The invention relates to a low-cost smelting technology of a converter, which belongs to the field of steel smelting. According to the smelting technology, a converter oxygen blowing process is divided into two stages, wherein in the first stage of high-efficiency dephosphorization, the oxygen blowing amount is controlled to be 13-18 Nm<3> each ton of iron, part of phosphorus-rich slag is poured out after the blowing, and 3-5 kg each ton of iron of sludge pellets are added when the blowing of the gun stops, thereby ensuring favoring slag pouring and the slag pouring rate of 40%-80%; in the second stage of less slag decarburization stage, a slag remaining and steel tapping mode is adopted at the terminal point of converter blowing. According to the smelting technology provided by the invention, converter lime is consumed at 10-20 kg each ton of steel, light burned dolomite is consumed at 5-12 kg each ton of steel, the phosphorus content of terminal molten steel can be steadily controlled to be below 0.013%, and the dephosphorization rate in the converter process is above 85%. Compared with the prior art, low-cost smelting technology has the beneficial effects that the use amounts of the converter lime and the light burned dolomite are reduced by 30%-50%, the consumption of the converter steel material is reduced by 5-6 kg each ton of steel, and the converter smelting cost is greatly reduced.

Description

A kind of converter low cost smelting technology

Technical field

The present invention relates to a kind of converter smelting process, be specifically related to a kind of converter low cost smelting technology producing Low-phosphorus Steel, belong to converter steelmaking field.

Background technology

Converter is with molten iron and steel scrap for raw material, and with the supplementary material such as lime, light dolomite for slag former, in stove, oxygen blast is smelted.The main purpose of converter smelting is dephosphorization, decarburization, intensification.The dephosphorisation reaction of kiln process can represent with formula <1>, and this reaction is thermopositive reaction, and favors low temperature carries out in the forward of dephosphorisation reaction.Utilize the low temperature environment bessemerizing the initial stage to build the oxidisability slag high efficiency dephosphorating of certain basicity, the then most rich phosphorus slag of fall stove removals, the phosphorus content of reduction total system, be conducive to the dephosphorizing capacity of raising later stage slag and reduce the probability of rephosphorization.

2[P]+5(FeO)+4(CaO)=(4CaO·P ₂O ₅)+[Fe]+Q <1>

Carbon is the topmost origin of heat of converter steelmaking, at the blowing initial stage in order to pursue higher dephosphorization rate, usually add a large amount of refrigerants and slow down being rapidly heated of molten bath, but lose more carbon, cause blowing later stage bath temperature can not reach molten steel requirement.This is the shortcoming of molten iron " three take off " pre-treatment and duplex converter, that is: molten iron (or half steel) temperature when being blended into converter decarburization is low, carbon content is low, needs to add a certain amount of carburelant or heat-generating agent supplements temperature at decarburizing phase.Thus, while the blowing initial stage improves dephosphorization efficiency, reducing the oxidation of carbon, is an importance of saving steel-making cost.

In addition, from dephosphorisation reaction formula, increasing basicity of slag (carrying high CaO content) and improving slag beneficiation (improving FeO content in slag) is two important factors promoting that reaction forward is carried out.Improve basicity of slag, increase the quantity of slag, while adding converter lime consumption, too increase iron loss, add the consumption of iron and steel stock.

Therefore, the less-slag melting technique developing a kind of low phosphorus content low cost is necessary.

Summary of the invention

The object of the invention is to provide a kind of converter low cost smelting technology, a upper stove terminal remaining slag operation is utilized to realize blowing first stage high efficiency dephosphorating, the deslagging operation terminated by dephosphorization achieves few slag decarburization of blowing subordinate phase, reach and reduce converter lime, light dolomite and steel technology, reduce the object of STEELMAKING PRODUCTION cost, smelting endpoint molten steel phosphorus content controls below 0.013% simultaneously.

For realizing the object of the invention: present invention employs following technical scheme:

A kind of converter low cost smelting technology, comprises first stage oxygen blast desiliconizing and dephosphorizing, and oxygen blast terminates to pour out the rich phosphorus slag of part, and the few slag decarburization of subordinate phase oxygen blast, finishing blowing stays slag to tap, and it is characterized in that: first stage blowing oxygen quantity is 13 ~ 18Nm ³oxygen rifle oxygen feeding stop during/ton iron, add ton iron 3 ~ 5kg mud pelletizing pressure slag while carrying rifle at oxygen rifle oxygen feeding stop, perform deslagging operation after pressure slag, deslagging rate is 40% ~ 80%; Subordinate phase top blast oxygen supply intensity is 3.5 ~ 3.7Nm ³/ mint, basicity of slag controls 2.8 ~ 3.5, and tapping temperature is more than 1630 DEG C.

Further, described mud pelletizing by weight percentage composition is: T.Fe:48 ~ 55%, MgO:2 ~ 7%, CaO:8 ~ 12%, SiO ₂<2%, P ₂o ₅<0.2%, Al ₂o ₃<0.5%, S<0.7%, P<0.07%, and the inevitable impurity of surplus.

The principal character of this technique is: (1) first stage oxygen blast terminates, while blow off carries rifle, add 3 ~ 5kg/t _{molten iron}mud pelletizing carries out pressure slag, can reduce thickness of slag layer fast, thus performs furnace operating smoothly, shortens the slagging time, and reduces temperature drop.Especially when molten iron initial silicon content is higher, foam slag blanket is higher close to fire door, and the stove that now falls is more dangerous, and the molten metal that deslagging is taken out of is many, must carry out pressure Slag treatment.In prior art, usually adopt before deslagging ore as pressure agent, adopt that mud pelletizing pressure slag add-on is less by comparison and successful, cost are lower.(2) have studied the relation of blowing initial stage molten bath phosphorus content and Converter Oxigen Blowing amount, control deslagging opportunity according to blowing oxygen quantity, show that the initial stage of bessemerizing performs the optimal selection opportunity of deslagging thus: ton iron oxygen-supplying amount is 13 ~ 18Nm ³time, adopt the low-basicity less quantity of slag to smelt after deslagging, supplementary product onsumption be lower, endpoint molten steel phosphorus content stablize.(3) bessemerizing terminal employing stays slag to tap, convert iron for safety to consider, have studied converter terminal slag to terminate during this period of time to slag splashing temperature changing regularity from tapping, slag composition according to this result and blow end point has formulated finishing slag residue adjustment scheme: add 2 ~ 4kg/t light dolomite after tapping and 1 ~ 2kg/t spatters slag agent, slag splashing terminate first to add steel scrap shake up after hot metal charging again.

This technique is applied in 180 tons of converters, and entering stove molten iron is conventional desulfurization preprocessed molten iron, allows molten iron silicon content to there is larger fluctuation range, does not need newly-increased dephosphorizing pretreatment equipment.Molten iron adopts the flow process of " a bag on earth ", and converter enters the temperature of stove molten iron at 1300 DEG C ~ 1450 DEG C, and it is less to bessemerize the subordinate phase quantity of slag, and improve the thermo-efficiency of carbon period, blow end point liquid steel temperature, more than 1630 DEG C, meets processing requirement.This technique realizes that terminal slag is hot is cycled to used in next stokehold phase dephosphorization, namely decreases slag emission, improves blowing first stage dephosphorization efficiency, again reduces the usage quantity of converter lime and light dolomite.First stage finishing blowing, pour out the rich phosphorus slag of 40% ~ 80%, obtain the lower molten iron of phosphorus content (also known as " half steel ", phosphorus content is 0.025% ~ 0.040%, carbon content is 3.0% ~ 3.2%), for later stage less-slag melting provides precondition, make to be easier to obtain high alkalinity high oxidative slag at blowing subordinate phase ratio, improve the dephosphorizing capacity of carbon period slag, providing safeguard for obtaining stable low-phosphorus molten steel.

The present invention adopts the molten iron without dephosphorizing pretreatment to be raw material, without under the condition of newly added equipment, achieve converter less-slag melting, reduce production cost, the consumption of converter lime and light dolomite reduces by 30% ~ 50%, steel technology reduces by 5 ~ 6kg/t, and converter steelmaking production cost reduces 20 ~ 25 yuan/ton.

Accompanying drawing explanation

Fig. 1 bessemerizes to terminate the Changing Pattern figure of later terminal slag temperature along with the time;

Fig. 2 is the graph of a relation of blowing initial stage molten bath phosphorus content and Converter Oxigen Blowing amount.

Embodiment

Below in conjunction with accompanying drawing and preferred embodiment, technical scheme of the present invention is further described.

Adopt converter low cost smelting technology of the present invention, with steel scrap and desulfurization preprocessed molten iron for raw material is smelted in converter, finishing slag can utilize by continuous circulation.Converter loaded condition, namely enter stove molten iron, steel scrap information as shown in table 1.

Oxygen supply system adopts the operating method of constant current quantitative change rifle position, and the oxygen blast flow of blowing desiliconizing and dephosphorizing phase first stage is about 36000Nm ³/ h, by opening the 1.9m ~ 2.1m blown, to be reduced to 1.6m ~ 1.65m(rifle position height gradually relevant with molten iron temperature and initial silicon content in rifle position); The oxygen blast flow of the few slag carbon period of blowing subordinate phase is about 39000Nm ³/ h, rifle position controls at 1.5m ~ 1.9m, and catch carbon rifle position is 1.5m.

Converter total amount of feeding in raw material is calculated by model, reinforced point 2 ~ 3 batches of the blowing first stage add, add 500 ~ 850kg sludge ball while blow off carries rifle before deslagging and carry out pressure Slag treatment, a reinforced point of multiple batches of short run of blowing subordinate phase adds in stove gradually, and the information such as the feeding quantity in each heat two blowing stage, blowing oxygen quantity, molten steel and slag composition are respectively as shown in table 2 ~ 6.

Table 1 loads molten iron and steel scrap information table

Reinforced and the oxygen blast information table of table 2 first stage blowing

Table 3 half composition of steel and temperature information table

Table 4 half steel slag ingredient (%) and basicity of slag table

Heat (batch) number	CaO	SiO ₂	P ₂O ₅	MgO	T·Fe	MnO	R
								Embodiment 1	30.548	19.31	3.654	6.87	13.22	9.05	1.58
Embodiment 2	31.864	19.20	3.731	9.62	11.71	7.51	1.66
								Embodiment 3	34.174	17.11	3.537	9.34	14.08	5.97	2.0

Embodiment 4

35.07

17.12

4.082

10.13

11.56

6.21

2.05

The oxygen blast of table 5 subordinate phase and reinforced information table

Table 6 endpoint molten steel composition (wt.%) and temperature (DEG C) information table

Although embodiment of the present invention are open as above, for those skilled in the art, can easily realize other amendment, therefore do not deviating under the universal that claim and equivalency range limit, the present invention is not limited to specific details.

Claims

1. a converter low cost smelting technology, comprises first stage oxygen blast desiliconizing and dephosphorizing, and oxygen blast terminates to pour out the rich phosphorus slag of part, and the few slag decarburization of subordinate phase oxygen blast, finishing blowing stays slag to tap, and it is characterized in that: first stage blowing oxygen quantity is 13 ~ 18Nm ³oxygen rifle oxygen feeding stop during/ton iron, at oxygen rifle oxygen feeding stop and add while carrying rifle 3 ~ 5kg/ ton iron mud pelletizing pressure slag, pressure slag after perform deslagging operation, deslagging rate is 40% ~ 80%; Subordinate phase top blast oxygen supply intensity is 3.5 ~ 3.7Nm ³/ (t _steelmin), basicity of slag controls 2.8 ~ 3.5, and tapping temperature is at 1630 ~ 1647 DEG C.

2. a kind of converter low cost smelting technology according to claim 1, is characterized in that: mud pelletizing composition is by weight percentage: T.Fe:48 ~ 55%, MgO:2 ~ 7%, CaO:8 ~ 12%, SiO ₂<2%, P ₂o ₅<0.2%, Al ₂o ₃<0.5%, S<0.7%, P<0.07%, and the inevitable impurity of surplus.

3. a kind of converter low cost smelting technology according to claim 1 and 2, is characterized in that: smelting endpoint molten steel phosphorus content controls below 0.013%.