CN104152634A - Method for stably controlling temperature in smelting process of AOD (argon oxygen decarburization) furnace - Google Patents

Abstract

The invention discloses a method for stably controlling the temperature in a smelting process of an AOD (argon oxygen decarburization) furnace. The method is characterized in that when the AOD furnace is used for producing stainless steel, a mother liquid is added into the AOD furnace firstly, alloys and slag materials are added, and the effective temperature of the mother liquid is calculated according to a formula; when the effective temperature of the mother liquid is a positive value, solid return scraps are added for cooling; and when the effective temperature of the mother liquid is a negative value, the position of an oxygen lance is adjusted to increase secondary burning capacity of CO gas. According to the method, the return material is flexibly applied while the oxidation quantity of chromium in the overall smelting process is reduced, and the purposes of shortening of smelting period, reduction of AOD furnace material consumption, prolonging of furnace age and fund release are achieved; the temperature in the smelting process of the AOD furnace can be controlled stably, chromium oxidation is reduced to the greatest extent, and consumption for reduction of silicon iron, lime and the like is reduced; and further, a large quantity of solid return scraps can be consumed while requirements of rapid decarburization and no additional increase of energy consumption between processes are met, and the production cost is effectively reduced.

Description

The stable control method of temperature in AOD stove smelting process

Technical field

The present invention relates to a kind of AOD stove smelting process, the stable control method of temperature in especially a kind of AOD stove smelting process.

Background technology

AOD stove is the abbreviation of argon oxygen decarburizing furnace (Argon Oxygen DeCarburization).In current stainless steel Production Flow Chart, AOD stove is being played the part of important role, and the whole world has and exceedes 70% stainless steel product and smelt by AOD stove according to statistics.It relies on side-blown good dynamics condition basis, realize decarburization and cr yield by lifting process temperature and the mode that reduces CO partial pressure, have equipment form simple, easy to operate, can use cheap high carbon ferro-chrome and return to stainless steel, easily produce the plurality of advantages such as low-carbon (LC) and Ultralow Carbon Stainless Steel.

But, for AOD stove, the significant temp (significant temp: the physics and chemistry temperature sum of mother liquor, deducts target temperature, deducts added alloy quantity of slag cooling, deducts the heat radiation of flue dust furnace lining again) that enters stove mother liquor (dephosphorization molten iron, containing Cr half molten steel etc.) directly affects the efficiency of decarburization and cr yield.Enter the conditional request that stove significant temp deficiency cannot meet Primary period decarburization and cr yield, will certainly increase the oxidation of chromium element, then cause the vicious cycle of lime, ferrosilicon consumption increase.Simultaneously, in decarburization latter stage, along with the reduction gradually of carbon in solution, inevitably there is oxidation in chromium element, causes temperature to continue to raise, and indivedual time periods can exceed the load softening point of the brick of resistance to material, cause the resistance to material of AOD to corrode aggravation.Therefore, in AOD stove smelting process, need to carry out quick temperature raising early stage in just refining, need to remain on metastable state latter stage could reduce the supplies consumption such as lime, ferrosilicon in decarburization, the while can be improved the stainless steel production capacity that safe operation coefficient and single stove are used as a servant.

And in actual production process, if had into stove significant temp deficiency, conventionally adopt the mode of increase last process energy consumption or interpolation ferrosilicon to improve the significant temp of mother liquor, this kind of mode can be avoided the oxidation of chromium element to a certain extent, affects the life-span in furnace life but can affect the normal running of last process and reduce AOD stokehold phase basicity of slag.

In sum, for AOD stove, it relies on good dynamic conditions basis, by promoting bath temperature, regulating oxygen and rare gas element ratio reduction CO dividing potential drop etc. that the principle of decarburization and cr yield is perfectly deduced.Be that high temperature that negative can not meet decarburization and cr yield is while requiring in the significant temp of initial mother liquor, there will be a large amount of oxidations of chromium element, and temperature can cause that if there is larger fluctuation Cr oxidation increases equally, then cause the increase of lime, ferrosilicon, fluorite consumption, cause the vicious cycle of furnace life reduction.

Summary of the invention

The technical problem to be solved in the present invention is to provide the stable control method of temperature in a kind of AOD stove smelting process that can effectively reduce the oxidation of chromium element.

For solving the problems of the technologies described above, the technical solution used in the present invention is: when described AOD stove is produced stainless steel, first mother liquor is blended into after AOD stove, top rifle carbon period adds high carbon alloy and slag charge, utilizes formula I to calculate mother liquor significant temp T ₁,

T ₁=T ₀+ T _{c, Si}-T _alloy-T _{slag charge}-T _{heat radiation}-T _{oxygen rifle target}i

In formula I:

T ₀-mother liquor initial temperature, DEG C;

T _{c, Si}the temperature of converting after carbon and silicon oxidation heat release in-mother liquor, DEG C;

T _alloythe temperature drop value of-alloy, DEG C;

T _{slag charge}the temperature drop value of-slag charge, DEG C;

T _{heat radiation}-flue dust, backup lining brick heat lost by radiation, DEG C;

T _{oxygen rifle target}target temperature when-oxygen rifle finishes, DEG C;

When mother liquor significant temp be on the occasion of time, add solid-state home scrap to lower the temperature; In the time that mother liquor significant temp is negative value, adjust the rifle position of oxygen rifle to increase the secondary combustion amount of CO gas.

Mother liquor significant temp of the present invention be on the occasion of time, the add-on M of solid-state home scrap ₁calculate by formula II,

$M_1=\frac{T_1}{K_1}\×1000---\left(\mathrm{II}\right)$

In formula II:

M ₁the add-on of-solid-state home scrap, kg;

T ₁-mother liquor significant temp, DEG C;

K ₁-1 ton of solid-state home scrap add the temperature drop DEG C in stove, its span is 30～40 DEG C, tap is the upper minimum value of getting in limited time, tap is the lower maximum value of getting in limited time.

When mother liquor significant temp of the present invention is negative value, adjust the rifle position of oxygen rifle at 2.9～3.3 meters; The temperature T that the secondary combustion of described CO gas provides ₂calculate by formula III,

$T_2=\frac{(W_1\×C_1\%+W_2\×C_2\%)}{W_1+W_2}\×100\×240\×K_2---\left(\mathrm{III}\right)$

In formula II:

W ₁-mother liquor initial weight, kg;

W ₂the weight of-top rifle high carbon alloy that the phase adds, kg;

C ₁-mother liquor initial carbon content, wt%;

C ₂-top rifle the phase adds the content of carbon in high carbon alloy, wt%;

K ₂-secondary combustion coefficient, K ₂value is 10%～15%; In the time of mother liquor initial carbon content≤2wt%, remove the limit capping when mother liquor initial carbon content>=3wt%;

The secondary combustion of described CO gas supplements T ₂while exceeding target temperature after temperature, while exceeding temperature>=40 DEG C, calculate and add home scrap according to formula II; While exceeding 40 DEG C of temperature <, reduce by 100～200m ³blowing oxygen quantity, and only use side-blown to carry out oxygen blast.

Of the present invention between top rifle carbon period and decarburization latter stage, use the mode of oxygen nitrogen vast scale or add≤500kg lime to adjust temperature.

Decarburization of the present invention latter stage is in the time that in solution in AOD stove, carbon content reaches below 0.10wt%, the solid-state home scrap of bulk that substance is exceeded to 500kg adds in stove, proceed oxygen decarburization until carbon content is less than target call 0.005～0.02wt% simultaneously, stop subsequently oxygen blast and add ferrosilicon, fluorite to reduce.The solid-state home scrap add-on of described bulk M ₂(kg) adopt formula IV to calculate,

$M_2=\frac{Q1}{100}\&times;K_3\&divide;K_4\&times;1000---\left(\mathrm{IV}\right)$

In formula IV:

Q ₁the blowing oxygen quantity in-decarburization latter stage, m ³;

K ₃-latter stage heating by O2 blowing coefficient, span is 25～35, tap is the lower maximum value of getting in limited time, tap is the upper minimum value of getting in limited time;

K ₄the solid-state home scrap temperature drop coefficient of-bulk, value unit 30～40, tap is the upper minimum value of getting in limited time, tap is the lower maximum value of getting in limited time.

AOD stove tap of the present invention, at 45～65 tons, is equipped with three holes or four hole Laval rifle heads and three side-blown air pressure guns.

In the heating element using in steel-making, carbon oxidation generates CO ₂the heat producing, much larger than the heat that generates CO, close to the thermal value of the element such as Si, Al, has good cost performance.In converting process, especially in the time of in earlier stage quick decarburization, carbon often only generates CO gas, this portion gas mixes outer row with high-temperature smoke and enters residual neat recovering system, fail to give full play to effective value in stove, increase CO gas secondary combustion ratio and realize the object of Primary period fast lifting bath temperature by improvement rifle head parameter, the mode that improves rifle position.Simultaneously, in producing stainless steel process, can produce the solid-state waste material that returns that accounts for ultimate production 5～15%, if electric furnace do not produce can only cause overstocked, be unfavorable for the turnover of fund, and the solid-state home scrap of bulk is wherein because density is higher, burn-off rate is slower, can utilize the fusing mode of its slow decorticating type to absorb decarburization oxygen blown intensification amount in latter stage, real-time temperature drop value is slightly less than and equals intensification value, realizing latter stage temperature does not increase, solve the problem that waste and old material secondary uses, reach shortening smelting cycle, reduce the supplies consumption of AOD stove, improve the object in furnace life.

The beneficial effect that adopts technique scheme to produce is: the present invention effectively solution never increases last process energy AOD stove initial smelting period significant temp deficiency consuming time or problem more than needed, solve the bath temperature causing simultaneously and continue the problem raising in the time of blowing oxygen blast in latter stage, in the amount of oxidation that reduces whole smelting process chromium element, will return to material flexible Application, reach the object that shortens smelting cycle, the supplies consumption of reduction AOD stove, improves furnace life, release fund.

The present invention can realize the steady control of AOD stove temperature in smelting process, reduces to greatest extent the oxidation of chromium element, reduces the consumption such as reduction ferrosilicon, lime; In completing quick decarburization, additionally not increasing the requirement of inter process energy consumption, also can consume a large amount of solid-state home scraps, thereby effectively reduce production costs.

Embodiment

Below in conjunction with specific embodiment, the present invention is further detailed explanation.

The stable control method of temperature in this AOD stove smelting process, mainly between the top rifle carbon period when the smelting stainless steel steel, top rifle carbon period and decarburization latter stage, the temperature of decarburization three main phase in latter stage rationally controls; It controls technique: the AOD stove tap of employing, at 45～65 tons, is equipped with three holes or four hole Laval rifle heads and three side-blown air pressure guns.

(1) top rifle carbon period:

First mother liquor is blended into after AOD stove, top rifle carbon period adds high carbon alloy and slag charge, utilizes formula I to calculate mother liquor significant temp T ₁,

T ₁=T ₀+ T _{c, Si}-T _alloy-T _{slag charge}-T _{heat radiation}-T _{oxygen rifle target}i

In formula I:

T ₀-mother liquor initial temperature, DEG C;

T _{c, Si}the temperature of converting after carbon and silicon oxidation heat release in-mother liquor, DEG C; Computing reference is [C%] * 110+[Si%] * 340, wherein C% is the quality percentage composition of carbon in mother liquor, Si% is the quality percentage composition of silicon in mother liquor;

T _alloythe temperature drop value of-alloy, DEG C; Computing reference is: (T _{oxygen rifle target}the initial temperature of-alloy)/W ₁-[W ₂* C ₁/ (W ₁+ W ₂) * 110+W ₂* C _si/ (W ₁+ W ₂) * 340], wherein C _sifor the quality percentage composition of Si in alloy;

T _{slag charge}the temperature drop value of-slag charge, DEG C; Computing reference is (T _{oxygen rifle target}the initial temperature of-slag charge)/W ₁;

T _{heat radiation}-flue dust, backup lining brick heat lost by radiation, DEG C; Computing reference is 80～100, and between heat, capping when dead time > 30min, gets middle limit when 20～30min, and < removes the limit when 20min;

T _{oxygen rifle target}target temperature when-oxygen rifle finishes, DEG C;

W ₁-mother liquor initial weight, kg;

W ₂the weight of-top rifle high carbon alloy that carbon period adds, kg;

C ₁-mother liquor initial carbon content, wt%;

(1) when mother liquor significant temp be on the occasion of time, add solid-state home scrap to lower the temperature; In the time that mother liquor significant temp is negative value, adjust the rifle position of oxygen rifle to increase the secondary combustion amount of CO gas.

Described mother liquor significant temp be on the occasion of time, the add-on M1 of solid-state home scrap by formula II calculate,

$M_1=\frac{T_1}{K_1}\&times;1000---\left(\mathrm{II}\right)$

In formula II:

M ₁the add-on of-solid-state home scrap, kg;

T ₁-mother liquor significant temp, DEG C;

K ₁-1 ton of solid-state home scrap add the temperature drop DEG C in stove, its span is 30～40 DEG C, tap is the upper minimum value of getting in limited time, tap is the lower maximum value of getting in limited time.

(2), when described mother liquor significant temp is negative value, adjust the rifle position of oxygen rifle at 2.9～3.3 meters; The temperature T that the secondary combustion of described CO gas provides ₂calculate by formula III,

$T_2=\frac{(W_1\&times;C_1\%+W_2\&times;C_2\%)}{W_1+W_2}\&times;100\&times;240\&times;K_2---\left(\mathrm{III}\right)$

In formula II:

W ₁-mother liquor initial weight, kg;

W ₂the weight of-top rifle high carbon alloy that carbon period adds, kg;

C ₁-mother liquor initial carbon content, wt%;

C ₂-top rifle carbon period adds the content of carbon in high carbon alloy, wt%;

K ₂-secondary combustion coefficient, K ₂value is 10%～15%; In the time of mother liquor initial carbon content≤2wt%, remove the limit capping when mother liquor initial carbon content>=3wt%;

The temperature T that the secondary combustion of described CO gas is supplementary ₂with supplement before temperature sum, while exceeding the target temperature that will reach, while exceeding temperature>=40 DEG C, calculate and add solid-state home scrap according to formula II; While exceeding 40 DEG C of temperature <, reduce by 100～200m ³blowing oxygen quantity, and only use side-blown to carry out oxygen blast.

(2) between top rifle carbon period and decarburization latter stage:

Described between top rifle carbon period and decarburization latter stage, use the mode of oxygen nitrogen vast scale or add≤500kg lime to adjust temperature; The volume ratio that described oxygen nitrogen vast scale refers to oxygen and nitrogen is between 5:1～12:1.

(3) decarburization latter stage:

Described decarburization latter stage is in the time that in solution in AOD stove, carbon content reaches below 0.10wt%, the solid-state home scrap of bulk that substance is exceeded to 500kg adds in stove, proceed oxygen decarburization until carbon content is less than target call 0.005～0.02wt% simultaneously, stop subsequently oxygen blast and add ferrosilicon, fluorite to reduce.The solid-state home scrap add-on of described bulk M ₂(kg) adopt formula IV to calculate,

$M_2=\frac{Q1}{100}\&times;K_3\&divide;K_4\&times;1000---\left(\mathrm{IV}\right)$

In formula IV:

Q ₁the blowing oxygen quantity in-decarburization latter stage, m ³;

K ₃-latter stage heating by O2 blowing coefficient, span is 25～35, tap is the lower maximum value of getting in limited time, tap is the upper minimum value of getting in limited time;

K ₄the temperature drop coefficient of the solid-state home scrap of-bulk, value unit 30～40, tap is the upper minimum value of getting in limited time, tap is the lower maximum value of getting in limited time.

Embodiment: (1) present method is on probation through Xing Gang workshop, by statistics, adopts former One-step production 0Cr13C steel grade technique, and adopts the consumption such as lime, ferrosilicon, fluorite of present method technique in table 1.

Table 1: composition and the correlated condition of initial material

(2) calculating significant temp according to above-mentioned condition is:

T ₁=-85 DEG C is negative, and top gun gun bit should be controlled between 2.9～3.3 meters, chooses 3.15 meters, simultaneously because the initial C of mother liquor is 3.5% (> 3%), therefore K ₂get 15%, according to T ₂formula calculates T ₂=159 DEG C, temperature surplus capacity is T ₁+ T ₂=-85+159=74 DEG C.

(3) top rifle phase home scrap add-on:

Said temperature surplus capacity is 94 DEG C of its value > 40, therefore the add-on of calculating solid-state returns according to formula II is M ₁=(74/30) * 1000=2460kg.

(4) the solid-state returns add-on in decarburization latter stage:

Decarburization thief carbon in latter stage content is 0.06%, and while taking off to target 0.02%, needing blowing oxygen quantity is 100m ³, the solid-state returns M that it added in latter stage ₂weight be calculated as according to formula IV: M ₂=1000kg;

(5) before and after calculating in the manner described above, process temperature becomes stable control, and each supplies consumption simultaneously obviously reduces, as shown in table 2:

Table 2: the raw material consumption amount contrast of former technique and this technique

?	Lime dosage kg	Solid-state home scrap kg	Fluorite kg	Ferrosilicon kg
					Former technique	5000	0	800	1500
This technique	4500	3000	680	1200

Claims (7)

1. a stable control method for temperature in AOD stove smelting process, is characterized in that: when described AOD stove is produced stainless steel, first mother liquor is blended into after AOD stove, top rifle carbon period adds high carbon alloy and slag charge, utilizes formula I to calculate mother liquor significant temp T ₁,

T ₁=T ₀+ T _{c, Si}-T _alloy-T _{slag charge}-T _{heat radiation}-T _{oxygen rifle target}i

In formula I:

T ₀-mother liquor initial temperature, DEG C;

T _{c, Si}the temperature of converting after carbon and silicon oxidation heat release in-mother liquor, DEG C;

T _alloythe temperature drop value of-alloy, DEG C;

T _{slag charge}the temperature drop value of-slag charge, DEG C;

T _{heat radiation}-flue dust, backup lining brick heat lost by radiation, DEG C;

T _{oxygen rifle target}target temperature when-oxygen rifle finishes, DEG C;

When mother liquor significant temp be on the occasion of time, add solid-state home scrap to lower the temperature; In the time that mother liquor significant temp is negative value, adjust the rifle position of oxygen rifle to increase the secondary combustion amount of CO gas.

2. the stable control method of temperature in AOD stove smelting process according to claim 1, is characterized in that: described mother liquor significant temp on the occasion of time, the add-on M1 of solid-state home scrap by formula II calculate,

$M_1=\frac{T_1}{K_1}\&times;1000---\left(\mathrm{II}\right)$

In formula II:

M ₁the add-on of-solid-state home scrap, kg;

T ₁-mother liquor significant temp, DEG C;

K ₁-1 ton of solid-state home scrap add the temperature drop DEG C in stove, its span is 30～40 DEG C, tap is the upper minimum value of getting in limited time, tap is the lower maximum value of getting in limited time.

3. the stable control method of temperature in AOD stove smelting process according to claim 1, is characterized in that: when described mother liquor significant temp is negative value, adjust the rifle position of oxygen rifle at 2.9～3.3 meters; The temperature T that the secondary combustion of described CO gas provides ₂calculate by formula III,

$T_2=\frac{(W_1\&times;C_1\%+W_2\&times;C_2\%)}{W_1+W_2}\&times;100\&times;240\&times;K_2---\left(\mathrm{III}\right)$

In formula II:

W ₁-mother liquor initial weight, kg;

W ₂the weight of-top rifle high carbon alloy that the phase adds, kg;

C ₁-mother liquor initial carbon content, wt%;

C ₂-top rifle the phase adds the content of carbon in high carbon alloy, wt%;

K ₂-secondary combustion coefficient, K ₂value is 10%～15%; In the time of mother liquor initial carbon content≤2wt%, remove the limit capping when mother liquor initial carbon content>=3wt%;

The secondary combustion of described CO gas supplements T ₂while exceeding target temperature after temperature, while exceeding temperature>=40 DEG C, calculate and add home scrap according to formula II; While exceeding 40 DEG C of temperature <, reduce by 100～200m ³blowing oxygen quantity, and only use side-blown to carry out oxygen blast.

4. the stable control method of temperature in AOD stove smelting process according to claim 1, is characterized in that: described between top rifle carbon period and decarburization latter stage, and use the mode of oxygen nitrogen vast scale or add≤500kg lime to adjust temperature.

5. the stable control method of temperature in AOD stove smelting process according to claim 1, it is characterized in that: described decarburization latter stage is in the time that in solution in AOD stove, carbon content reaches below 0.10wt%, the solid-state home scrap of bulk that substance is exceeded to 500kg adds in stove, proceed oxygen decarburization until carbon content is less than target call 0.005～0.02wt% simultaneously, stop subsequently oxygen blast and add ferrosilicon, fluorite to reduce.

6. the stable control method of temperature in AOD stove smelting process according to claim 5, is characterized in that: the solid-state home scrap add-on of described bulk M ₂(kg) adopt formula IV to calculate,

$M_2=\frac{Q1}{100}\&times;K_3\&divide;K_4\&times;1000---\left(\mathrm{IV}\right)$

In formula IV:

Q ₁the blowing oxygen quantity in-decarburization latter stage, m ³;

K ₃-latter stage heating by O2 blowing coefficient, span is 25～35, tap is the lower maximum value of getting in limited time, tap is the upper minimum value of getting in limited time;

K ₄the solid-state home scrap temperature drop coefficient of-bulk, value unit 30～40, tap is the upper minimum value of getting in limited time, tap is the lower maximum value of getting in limited time.

7. according to the stable control method of temperature in the AOD stove smelting process described in claim 1-6 any one, it is characterized in that: described AOD stove tap, at 45～65 tons, is equipped with three holes or four hole Laval rifle heads and three side-blown air pressure guns.