CN114525378A - Method for determining average carbon content of mixed scrap steel based on Consteel electric arc furnace - Google Patents

Method for determining average carbon content of mixed scrap steel based on Consteel electric arc furnace Download PDF

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CN114525378A
CN114525378A CN202210103199.5A CN202210103199A CN114525378A CN 114525378 A CN114525378 A CN 114525378A CN 202210103199 A CN202210103199 A CN 202210103199A CN 114525378 A CN114525378 A CN 114525378A
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steel
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carbon content
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CN114525378B (en
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李晶
李波
王岩
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University of Science and Technology Beijing USTB
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/52—Manufacture of steel in electric furnaces
    • C21C5/527—Charging of the electric furnace
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/52—Manufacture of steel in electric furnaces
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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Abstract

The invention discloses a method for determining the average carbon content of mixed scrap steel based on a Consteel electric arc furnace, belonging to the field of steel process flow smelting control. The method comprises the following steps: firstly, adding a certain amount of carbon balls into the furnace at one time through a bin at the beginning of smelting; adding mixed steel scrap composed of different material types in the same batch into the furnace through a continuous preheating horizontal channel, wherein the steel scrap adding speed is constant; feeding power at the beginning of smelting, adding slag and supplying oxygen; spraying carbon powder into the furnace when smelting begins; and (4) carrying out component detection on the steel sample twice, and determining and verifying the average carbon content of the mixed steel scrap according to the component content. The method comprises the steps of determining the average carbon content of mixed steel scraps according to a first sampling result, forecasting and guiding the carbon content at the smelting end point of the furnace, verifying the effectiveness of the determined average carbon content of the mixed steel scraps of the same batch according to a secondary sampling result before tapping, and forecasting the carbon content of the next molten steel in a Consteel electric arc furnace for smelting by taking the mixed steel scraps of the same batch as iron-containing raw materials.

Description

Method for determining average carbon content of mixed scrap steel based on Consteel electric arc furnace
Technical Field
The invention relates to the field of steel process flow smelting control, in particular to a method for determining the average carbon content of mixed scrap steel based on a Consteel electric arc furnace.
Background
The method for determining the average carbon content of the mixed scrap steel is very important, and is very favorable for reducing the cost of steel per ton by using a stable operation process of a full-scrap steel Consteel electric arc furnace.
In the smelting process of the full-scrap steel continuous horizontal charging electric arc furnace, because scrap steel of different material types is slowly added into the electric arc furnace through a horizontal preheating charging channel after being mixed, and foam slag is required to carry out submerged arc heating on electrodes in the smelting process, the smelting technology of whole-process oxygen supply and carbon distribution in the furnace is required to be adopted. If the average carbon content of the mixed steel scraps of different material types of the same batch is determined, reasonable carbon distribution and efficient oxygen supply to a molten pool in the smelting process must be met, and if the oxygen supply amount, the oxygen supply mode, the carbon distribution amount and the carbon distribution mode are unreasonable, the problems of metal molten pool peroxidation or high carbon content in the molten pool and the like can be caused, so that the average carbon content of the mixed steel scraps of different material types of the same batch cannot be accurately determined.
Disclosure of Invention
The invention provides a method for determining the average carbon content of mixed scrap steel based on a Consteel electric arc furnace. The steel remaining amount in the furnace before smelting is started is more than 35 percent of the steel tapping amount, the steel remaining liquid has known components, the steel remaining temperature is more than 1570 ℃, and the physical heat in the furnace is sufficient. Firstly, a certain amount of carbon balls are added into a metal molten pool at one time at the beginning of smelting, and the carbon balls are added within 3min from the beginning of smelting. Meanwhile, mixed steel scrap composed of different material types in the same batch is added into the furnace through the continuous preheating horizontal channel, the speed of adding the steel scrap is basically constant at 3.2t/min, power is supplied immediately when smelting is started, slag and oxygen are added, all slag is completely added within 18min, the oxygen is supplied by the furnace wall oxygen lance and the furnace door oxygen lance, the smelting process is reasonable and efficient, and the phenomenon of peroxidation of a metal molten pool is avoided. The carbon powder spraying speed is basically constant in the smelting process. In the whole smelting process, two times of steel samples are taken for component detection, the time for sampling once is 22-25min for smelting, and secondary sampling is carried out before tapping at the smelting end point. The method comprises the steps of determining the average carbon content of mixed steel scraps according to the components of molten steel sampled for the first time and the energy consumption condition, playing a role in forecasting and guiding the furnace end point carbon content, verifying the effectiveness of the determined average carbon content of the mixed steel scraps in the same batch according to secondary sampling and the energy consumption condition before steel tapping, and forecasting the carbon content of the next molten steel in a Consteel electric arc furnace for smelting by taking the mixed steel scraps in the same batch as iron-containing raw materials.
According to the technical solution of the present invention, there is provided a method for determining the average carbon content of mixed scrap based on a Consteel electric arc furnace, which is a continuous horizontal charging electric arc furnace having a metal bath (all Consteel electric arc furnaces have steel-leaving operation in case of continuous smelting production), a continuous preheating horizontal passage (inherent structural component of the Consteel electric arc furnace), a furnace wall oxygen lance (inherent structural component of the Consteel electric arc furnace), a furnace door carbon lance (inherent structural component of the Consteel electric arc furnace), and a furnace wall carbon lance (inherent structural component of the Consteel electric arc furnace), characterized in that the type of steel to be smelted is plain carbon steel, the method comprising the steps of:
step 1: firstly, adding a certain amount of carbon balls into a metal molten pool at one time at the beginning of smelting;
step 2: adding mixed steel scrap composed of different material types in the same batch into the furnace through a continuous preheating horizontal channel, wherein the steel scrap adding speed is constant;
and step 3: feeding power at the beginning of smelting, adding slag and supplying oxygen;
and 4, step 4: spraying carbon powder into the furnace when smelting begins;
and 5: and respectively carrying out component detection on the steel sample twice, and determining and verifying the average carbon content of the mixed steel scraps according to the component content.
Further, before the step 1, the steel remaining quantity in the furnace before smelting is started is more than 35% of the steel tapping quantity, the steel liquid remaining component is known, and the physical heat in the furnace is sufficient. The steel remaining amount is more than 35 percent of the steel tapping amount, so that the steel remaining amount is enough, the physical heat of the steel remaining is sufficient, the electric energy input and the chemical heat input in the furnace can be reduced in the smelting process, and the effects of saving energy and reducing consumption can be achieved.
Further, the components of the steel liquid remained are the final components of the steel liquid in the last furnace.
Further, in the step 1, the carbon balls are added at one time within 3min after the smelting is started. The purpose of adding carbon balls at one time when smelting is started is as follows: (1) the carbon content in the metal melting pool is low at the beginning of smelting, oxygen is supplied at the beginning of smelting, and in order to prevent the molten steel from being oxidized, carbon balls are required to be added at one time to rapidly and greatly carburete in the furnace; (2) slag materials are added at the beginning of smelting, and the carbon balls are added at one time to generate violent oxidation reaction with oxygen blown into the furnace, so that a large amount of CO gas and chemical reaction heat are generated, and rapid slagging and foam slag making are facilitated to be buried in electric arcs for heating.
Further, in the step 3, all the slag materials are completely added within 18 min. The time can utilize the physical heat of a large amount of steel left in the early stage of smelting and a large amount of chemical heat generated by adding the carbon balls to quickly melt slag and form slag, is favorable for energy conservation and consumption reduction, and is favorable for stably blowing carbon powder and stably supplying oxygen to produce foam slag in the smelting process.
Furthermore, in the step 3, oxygen supply is completed by a furnace wall oxygen lance and a furnace door oxygen lance, so that oxygen is supplied reasonably and efficiently in the smelting process, and the phenomenon of peroxidation of a metal molten pool is avoided; oxygen lance oxygen supply flow can be finely adjusted according to the slag overflow condition of the furnace door opening.
Further, in the step 4, the carbon powder spraying rate is basically constant in the smelting process, and the carbon powder spraying is completed by a furnace door carbon gun and a furnace wall carbon gun.
Further, the step 5 specifically includes:
step 51: beginning to smelt for 22-25min, taking a steel sample for first component detection, and determining the average carbon content of the mixed scrap steel according to the first component detection result;
step 52: taking a steel sample before tapping at the smelting end point for secondary component detection, thereby verifying the effectiveness of the determined average carbon content of the mixed steel scrap of the same batch, and simultaneously forecasting the carbon content of a molten pool of the next molten steel of the same batch; and verifying the validity of the average carbon content of the mixed steel scraps according to the second component detection result.
Here, the purpose of one sampling at 22-25min in step 51 is: (1) according to the operation steps, when smelting is started for 22-25min, a large amount of newly generated molten steel exists in a metal melting pool in the furnace, along with the rise of the molten steel surface in the furnace, a steel sample is taken for component detection 22-25min, so that molten steel components with uniform components can be obtained, and the detection result of the molten steel components is more real and reliable; (2) the whole smelting time is 35-40min, the time interval between the primary sampling and the secondary sampling cannot be too short, the time interval is too short and is not enough, and enough time is reserved between the primary sampling and the secondary sampling at the smelting end point; (3) the average carbon content of the mixed steel scraps is determined according to the molten steel components and the energy consumption condition of the first sampling, and the function of forecasting and guiding the furnace end point carbon content is achieved.
Further, in the step 51, determining the average carbon content of the mixed steel scraps according to the first component detection result is realized according to the following formula:
Figure BDA0003492904480000031
wherein:
Mscrap Steel 1The amount of scrap steel, kg, added from the beginning of smelting to the first sampling;
[％Cscrap steel]-average carbon content of mixed scrap,%;
Mcarbon ball-the amount of carbon spheres added, kg;
Mcarbon powder 1The amount of the carbon powder added from the beginning of smelting to the first sampling period is kg;
Mretained steel-leaving the mass of steel in kg;
[％Cretained steel]-residual steel carbon content,%;
[％Csample 1]-sampling carbon content,%;
Δ1O2-oxygen consumption, Nm, from the start of the smelting to the sampling3；
f-Metal yield,%;
Figure BDA0003492904480000041
-oxygen utilization for decarburization,%;
Figure BDA0003492904480000042
-1 kg of carbonAmount of oxygen consumed for the oxidation reaction to take place, Nm3/kg。
Principle of formula (1): during the time period from the beginning of smelting to the first component detection of the steel sample, according to the change of the carbon mass in the electric furnace and the oxygen consumption, in combination with the oxidation reaction of carbon, an equality relation is established, and the unknown [% C is obtained by solvingScrap steel]-average carbon content of mixed scrap,%.
Further, in the step 52, the tapping temperature at the smelting end point is as follows: t is more than 1580 ℃.
Further, in the step 52, verifying the validity of the average carbon content of the mixed steel scrap according to the second component detection result is realized according to the following formula:
Figure BDA0003492904480000043
wherein:
Mscrap Steel 1The amount of scrap steel, kg, added from the beginning of smelting to the first sampling;
[％Cscrap steel]-average carbon content of mixed scrap,%;
Mretained steel-leaving the mass of steel in kg;
[％Csample 1]-sampling carbon content,%;
Mscrap Steel 2-the amount of scrap steel, kg, added during the period from the primary sampling to the secondary sampling;
Mcarbon powder 2-the amount of carbon powder added, kg, from the first sampling to the second sampling;
[％Csample 2]-carbon content of secondary sample,%;
Δ2O2oxygen consumption, Nm, from primary to secondary sampling3；
f-metal yield,%;
Figure BDA0003492904480000044
-oxygen utilization for decarburization,%;
Figure BDA0003492904480000045
1kg of oxygen consumed by the oxidation of carbon, Nm3/kg。
Principle of equation (2): during the time period from the first steel sample component detection to the second steel sample component detection, an equality relation is established according to the change of carbon quality and oxygen consumption in the electric furnace and the oxidation reaction of carbon, and the unknown [% C is obtained by solvingScrap steel]-average carbon content of mixed scrap,%;
equivalent to calculating [% C twiceScrap steel]The equation (1) is solved by establishing an equality relationship between the oxygen consumption and the change in the mass of carbon in the furnace during the first half of the smelting period (from the beginning of smelting to the first sampling), the equation (2) is solved by establishing an equality relationship between the oxygen consumption and the change in the mass of carbon in the furnace during the second half of the smelting period (from the first sampling to the second sampling), and the calculation results obtained by the two calculations are basically consistent (the following specific implementation mode shows that the difference between the calculation results of the two calculations is about 0.003 percent), so that the method for determining the average carbon content of the mixed scrap steel is established.
The invention has the following advantages and beneficial effects:
(1) the method is simple and convenient to operate and easy to master, under the conditions of efficient oxygen supply and reasonable carbon distribution, the average carbon content of the mixed steel scraps is determined according to the molten steel components and energy consumption conditions of the first sampling, and then the effectiveness of the average carbon content of the mixed steel scraps of the same batch is verified according to the secondary sampling before tapping.
(2) The method is favorable for carrying out high-efficiency control on the steelmaking process of the electric arc furnace by using the mixed steel scraps of the same batch with known average carbon content as the iron-containing raw materials through determining the average carbon content of the mixed steel scraps of different material types, improves the control level of the carbon content at the smelting end point of the electric arc furnace, and can forecast the molten pool carbon content of the next molten steel smelted by using the mixed steel scraps of the same batch with known average carbon content.
(3) The method can determine the average carbon content of mixed steel scraps of different material types in the same batch under the condition of not influencing normal electric arc furnace production and energy consumption, reduce the alloy addition amount after the furnace, and effectively reduce the cost of steel per ton.
Detailed Description
The technical solution of the present invention is further described with reference to the following specific embodiments.
The invention discloses a method for determining the average carbon content of mixed scrap steel based on a Consteel electric arc furnace, which specifically comprises the following steps: the electric arc furnace is a continuous horizontal charging type electric arc furnace, mixed steel scrap is composed of different material types in the same batch, the mixed steel scrap is uniformly distributed on a continuous charging horizontal preheating channel, the speed of charging the steel scrap is basically constant, the speed of spraying carbon powder in the smelting process is basically constant, the oxygen supply operation is reasonable and efficient, the blowing-in of oxygen is ensured to be efficient, and the phenomenon of over oxidation of a metal melting pool is avoided. And in the smelting process of each furnace, two times of steel samples are taken for component detection, wherein one time of sampling is carried out when smelting is started for 22-25 minutes, and two times of sampling are carried out before end point tapping. The average carbon content of the mixed steel scraps is determined according to the components of the molten steel sampled for the first time and the energy consumption condition, the function of forecasting and guiding the furnace end point carbon content is achieved, the effectiveness of the determined average carbon content of the mixed steel scraps in the same batch is verified according to the secondary sampling and the energy consumption condition before steel tapping, and meanwhile, the carbon content of a molten pool of the next molten steel in the same batch can be forecasted.
The raw materials used for the steel making of the electric arc furnace are mixed scrap steel, and the carbon content of the mixed scrap steel of different material types is unknown, so that the electric arc furnace smelting end point control effect is not ideal, and the difficulty in forecasting the smelting end point components is high. The invention controls the oxygen supply flow of the furnace door and the furnace wall oxygen lance by reasonably distributing carbon, determines the average carbon content of the mixed steel scraps of different material types in the same batch by sampling twice in the smelting process, the mixed steel scraps in the same batch can be continuously smelted for a plurality of times, and the Consteel arc furnace is continuously filled with the mixed steel scraps of the same batch with known average carbon content for smelting, thereby being beneficial to guiding the oxygen supply operation in the smelting process, improving the carbon content control level of the smelting end point molten steel and avoiding the molten steel peroxidation.
Example 1
Steel remains in the furnace for 45.8 tons and [ C ]]: 0.120 percent, the steel-remaining temperature is 1575 ℃, 300kg of carbon balls are added at the beginning of smelting, the speed of adding the scrap steel is constant at 3.2t/min, the first sampling time is 23.6min of beginning smelting, and a steel sample [ C ] is taken for the first time]: 0.217%, the second sampling time was 36.5min, and the steel sample [ C ] was taken for the second time]:0.117 percent, the steel tapping amount is 88.5t, the total slag charge consumption is 39.76kg/t, the oxygen consumption is 35.06Nm3And t, the tapping temperature is 1583 ℃.
The method mainly comprises the following steps:
(1) after the last furnace EBT finishes tapping, steel remained in the furnace is more than 35 percent of the tapping quantity, MRetained steel45.8 tons of steel liquid, the component of the steel liquid is the end point component of the last furnace steel smelting, [% CRetained steel]0.12 percent, leaving the steel at 1575 ℃;
(2) firstly, adding M into a metal molten pool at one time at the beginning of smeltingCarbon ballIncreasing the carbon content of the molten pool by 300kg, finishing adding carbon balls within 3min of starting smelting, and spraying carbon powder into the furnace while adding the carbon balls.
(3) And adding mixed steel scraps consisting of different material types in the same batch into the furnace through a continuous preheating horizontal channel, wherein the steel scrap adding speed is constant at 3.2 t/min.
(4) When smelting begins, power is supplied, slag charge and oxygen supply are carried out, all slag charges are completely charged within 18min, the oxygen supply is completed by a furnace wall oxygen lance and a furnace door oxygen lance, and the smelting process is reasonable and efficient. Wherein the oxygen supply flow of the furnace door oxygen lance is 3100Nm3·h-1(35Nm3·h-1·t-1) The oxygen supply flow of the furnace wall oxygen lance is 2000Nm3·h-1(23Nm3·h-1·t-1) And the phenomenon of over oxidation of the molten metal pool is avoided. The oxygen supply flow of the oxygen lance can be finely adjusted according to the slag overflow condition at the furnace door, and the oxygen supply flow of the furnace door oxygen lance and the furnace wall oxygen lance can be adjusted within the variation range of +/-500 Nm3·h-1(6Nm3·h-1·t-1) And the total sum of the oxygen supply flow of the furnace door oxygen lance and the furnace wall oxygen lance is required to be kept unchanged all the time during adjustment.
(5) The carbon powder spraying speed is basically constant in the smelting process, and the average speed is 45 kg/min. The carbon powder spraying is completed by a furnace door carbon gun and two furnace wall carbon guns, wherein the carbon powder spraying speed of the furnace door carbon gun is 18kg/min, and the carbon powder spraying speed of the two furnace wall carbon guns is 13.5 kg/min.
(6) Beginning to smelt at 23.6min, taking a steel sample for component detection, and taking the steel sample [% C ] for the first timeSample 1]＝0.217％。
(7) Determining the average carbon content of the mixed steel scraps:
Figure BDA0003492904480000071
wherein:
Mscrap Steel 13.2 × 23.6 × 1000 ═ 75520kg, the amount of scrap added from the start of the smelting to the first sampling;
Mcarbon ball300kg, which is the adding amount of the carbon spheres;
Mcarbon powder 123.6 x 45 x 1062kg, which is the amount of carbon powder added from the beginning of smelting to the first sampling;
Mretained steel45.8 × 1000 × 45800kg, which is the retained steel mass;
[％Cretained steel]0.12 percent of the total carbon content of the steel;
[％Csample 1]0.217%, which is the carbon content of the primary sample;
Δ1O2＝23.6/60*5100＝2006Nm3oxygen consumption from the beginning of smelting to the first sampling period;
Figure BDA0003492904480000074
taking 0.8 as the oxygen utilization rate for decarburization;
f, taking 0.9 as the metal yield;
Figure BDA0003492904480000072
the oxygen consumption is 1kg of the oxygen consumed by the oxidation reaction of carbon;
substitution formula (1) to [% CScrap steel]＝0.715％；
(8) The method for verifying the effectiveness of the determined average carbon content of the mixed steel scraps of the same batch according to secondary sampling before tapping comprises the following steps:
Figure BDA0003492904480000073
Mscrap Steel 23.2 (36.5-23.6) 1000 41280kg, the amount of scrap added from the first sampling to the second sampling;
Mcarbon powder 2(36.5-23.6) × 45 ═ 580.5kg, the amount of carbon powder added from the first sampling to the second sampling;
[％Csample 1]0.217%, which is the carbon content of the primary sample;
Mscrap Steel 13.2 × 23.6 × 1000 ═ 75520kg, the amount of scrap added from the start of the smelting to the first sampling;
Mretained steel45.8 × 1000 × 45800kg, which is the retained steel mass;
[％Csample 2]0.117% as carbon content of the second sample;
Δ2O2＝(36.5-23.6)/60*5100＝1096.5Nm3oxygen consumption from the first sampling to the second sampling;
Figure BDA0003492904480000081
taking 0.8 as the oxygen utilization rate for decarburization;
f, taking 0.9 as the metal yield;
Figure BDA0003492904480000082
the oxygen consumption is 1kg of the oxygen consumed by the oxidation reaction of carbon;
substitution formula (2) to [% CScrap steel]＝0.712％；
The average carbon content of the mixed steel scraps with different material types and compositions of the batch is determined to be 0.71 percent.
Example 2
This heat was the next heat next to example 1, leaving 48.3t of steel in the furnace, leaving steel [ C ]]0.117%, remainThe steel temperature is 1573 ℃, 300kg of carbon balls are added at the beginning of smelting, the speed of adding the waste steel is constant at 3.2t/min, the first sampling time is 24.1min of beginning of smelting, and a steel sample [ C ] is taken for the first time]: 0.209%, the second sampling time was 37.9min, and the steel sample [ C ] was taken for the second time]: 0.111 percent, the steel tapping amount is 88.7t, the total slag charge consumption is 40.59kg/t, and the oxygen consumption is 36.32Nm3T, the tapping temperature is 1588 ℃.
Figure BDA0003492904480000083
MScrap Steel 124.1 × 3.2 × 1000 × 77120kg, the amount of scrap added from the start of the smelting to the first sampling;
[％Cscrap steel]0.71 percent, which is the average carbon content of the mixed steel scraps of the same batch and different material types, and is determined by the last furnace;
Mcarbon ball300kg, which is the addition amount of carbon spheres;
Mcarbon powder 124.1 × 45 × 1084.5kg, which is the amount of carbon powder added from the beginning of smelting to the first sampling;
Mretained steel48.3 × 1000 × 48300kg, which is the retained steel mass;
[％Cretained steel]0.117% of the total carbon content of the steel;
Δ1O2＝24.1/60*5100＝2048.5Nm3oxygen consumption from the beginning of smelting to the first sampling period;
Figure BDA0003492904480000091
taking 0.8 as the oxygen utilization rate for decarburization;
f, taking 0.9 as the metal yield;
Figure BDA0003492904480000095
the oxygen consumption is 1kg of the oxygen consumed by the oxidation reaction of carbon;
substitution formula (1) to [% CSample 1]0.206%, and the actual first steel sample [% C [% ]Sample 1]The carbon content of the molten pool of the adjacent heat of the electric furnace for smelting by using the same batch of mixed scrap as the iron-containing raw material can be effectively predicted under the condition that the carbon content of the mixed scrap is known.
Figure BDA0003492904480000092
MScrap Steel 23.2 (37.9-24.1) 1000 44160kg, which is the amount of scrap added from the first sampling to the second sampling;
[％Cscrap steel]0.71 percent of the total carbon content of the same batch of mixed scrap steel with different material types;
Mcarbon powder 2(37.9-24.1) × 45 ═ 621kg, the amount of carbon powder added from the first sampling to the second sampling;
[％Csample 1]0.209%, which is the carbon content of the primary sample;
Mscrap Steel 124.1 × 3.2 × 1000 — 77120kg, the amount of scrap added from the start of the smelting to the first sampling;
Mretained steel48300kg of steel as the retained mass;
Δ2O2＝(37.9-24.1)/60*5100＝1173Nm3oxygen consumption from the first sampling to the second sampling;
Figure BDA0003492904480000093
taking 0.8 as the oxygen utilization rate for decarburization;
f, taking 0.9 as the metal yield;
Figure BDA0003492904480000094
the oxygen consumption is 1kg of the oxygen consumed by the oxidation reaction of carbon;
substitution formula (2) to [% CSample 2]0.108%, and the second time of actual sampling steel sample [% CSample 2]0.111% is substantially identical, indicating that under known conditions of mixed scrap carbon content, the same can be used with effective predictionThe carbon content of a molten pool of an adjacent furnace of an electric furnace for smelting by using the batch mixed scrap steel as the iron-containing raw material.
Example 3
Leaving 50.7 tons of steel in the furnace and leaving steel [ C ]]: 0.107 percent, the steel-remaining temperature is 1573 ℃, 300kg of carbon balls are added at the beginning of smelting, the speed of adding the scrap steel is constant at 3.2t/min, the first sampling time is 24.5min for beginning smelting, and a steel sample [ C ] is taken for the first time]: 0.239%, the second sampling time is 37.8min, and the steel sample [ C ] is taken for the second time]:0.152 percent, the steel tapping amount is 87.9t, the total consumption of slag charge is 40.96kg/t, the oxygen consumption is 36.55Nm3And t, the tapping temperature is 1589 ℃. The average carbon content of the mixed steel scraps with different material types of the batch determined by the primary sampling calculation is 0.774%, and the average carbon content of the mixed steel scraps of the same batch determined by the secondary sampling verification before tapping is 0.771%. The average carbon content of the mixed steel scraps with different material types and compositions of the batch is determined to be 0.77 percent.
Example 4
The heat is next to that of example 3, 47.6t of steel is left in the furnace, and [ C ] is left]0.152 percent, the steel-remaining temperature is 1577 ℃, 300kg of carbon balls are added at the beginning of smelting, the speed of adding the steel scrap is constant at 3.2t/min, the average carbon content of the mixed steel scrap in the same batch is 0.77 percent, the first sampling time is 24.7min of beginning smelting, and the first actual steel sample is detected to obtain [ C]: 0.259%, calculated according to the known conditions substituting into equation (1) [% CSample 1]0.256%, the second sampling time is 38.5min, and the second actual sampling of steel sample [ C [ ]]: 0.166 percent, the steel tapping amount is 88.7t, the total slag charge consumption is 40.59kg/t, the oxygen consumption is 36.89Nm3And t, the tapping temperature is 1586 ℃. Calculated as [% C by substituting equation (2) according to known conditionsSample 2]And when the carbon content of the molten steel is 0.163 percent, the carbon content of the molten steel actually sampled twice is basically consistent with the carbon content of the molten steel calculated by respectively substituting the formula (1) and the formula (2) according to the known conditions, which indicates that the carbon content of a molten pool of an electric furnace adjacent to an electric furnace for smelting by using the same batch of mixed scrap as the iron-containing raw material can be effectively predicted under the condition of the known carbon content of the mixed scrap.
Example 5
Leaving 40.3 tons of steel in the furnace and leaving steel [ C ]]: 0.139 percent, the steel temperature is 1571 ℃, and smelting is started firstAdding 300kg of carbon balls, wherein the scrap adding speed is constant at 3.2t/min, the first sampling time is 23.3min after smelting is started, and a steel sample [ C ] is taken for the first time]: 0.207%, the second sampling time is 35.2min, and the steel sample [ C ] is taken for the second time]:0.102 percent, the steel tapping amount is 88.2t, the total slag charge consumption is 40.82kg/t, and the oxygen consumption is 33.92Nm3And t, the tapping temperature is 1589 ℃. The average carbon content of the mixed steel scraps with different material types of the batch determined by the primary sampling calculation is 0.681%, and the average carbon content of the mixed steel scraps with different material types of the batch is 0.68% according to the determined average carbon content of the same batch of mixed steel scraps by the secondary sampling verification before tapping.
Example 6
This heat was the next heat next to example 5, leaving 43.9t of steel in the furnace and leaving steel [ C ]]0.102 percent, the steel-remaining temperature is 1579 ℃, 300kg of carbon balls are added when smelting is started, the steel scrap adding speed is constant at 3.2t/min, the average carbon content of mixed steel scrap in the same batch is 0.68 percent, the first sampling time is 24.3min when smelting is started, and the steel sample is actually taken for the first time to be detected and measured to obtain [ C [, C [ ]]: 0.183%, calculated [% C) according to the known conditions substituting into equation (1)Sample 1]0.179%, the second sampling time is 38.1min, and the second actual sampling of steel sample [ C%]: 0.081 percent, the steel tapping amount of 88.7t, the total slag charge consumption of 40.59kg/t and the oxygen consumption of 36.51Nm3And t, the tapping temperature is 1586 ℃. Calculated as [% C by substituting equation (2) according to known conditionsSample 2]And (3) 0.078 percent, wherein the carbon content of the molten steel actually sampled twice is basically consistent with the carbon content of the molten steel calculated according to the known conditions and respectively carried into the formula (1) and the formula (2), which shows that under the condition of the known carbon content of the mixed scrap steel, the carbon content of a molten pool of an adjacent furnace of an electric furnace for smelting by using the same batch of mixed scrap steel as a ferrous raw material can be effectively predicted.
Therefore, the method has the advantages of simple process flow and convenient operation, and can effectively determine the average carbon content of the mixed steel scraps of the same batch and different material types.
While embodiments of the present invention have been described, the present invention is not limited to the above-described embodiments, which are intended to be illustrative rather than limiting, and many modifications may be made by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (10)

1. A method for determining the average carbon content of mixed scrap based on a Consteel electric arc furnace having a continuous preheating horizontal passage, a furnace wall oxygen lance, a furnace door carbon lance and a furnace wall carbon lance, characterized in that the steel being smelted is plain carbon steel, said method comprising the steps of:
step 1: firstly, adding a certain amount of carbon balls into the furnace at one time through a bin at the beginning of smelting;
and 2, step: adding mixed steel scrap composed of different material types in the same batch into the furnace through a continuous preheating horizontal channel, wherein the steel scrap adding speed is constant;
and step 3: feeding power at the beginning of smelting, adding slag and supplying oxygen;
and 4, step 4: spraying carbon powder into the furnace when smelting begins;
and 5: and respectively carrying out twice component detection on the steel sample, and determining and verifying the average carbon content of the mixed steel scraps according to the component content.
2. The method of claim 1, wherein the amount of steel left in the furnace before the start of the smelting is more than 35% of the steel tapping amount, the composition of the molten steel is known, and the physical heat in the furnace is sufficient before the step 1.
3. The method according to claim 1, wherein in the step 1, the carbon balls are added at one time within 3min from the beginning of smelting.
4. The method according to claim 1, wherein in step 3, all the slag is added within 18 min.
5. The method according to claim 1, wherein in the step 3, oxygen supply is completed by a furnace wall oxygen lance and a furnace door oxygen lance, and oxygen supply is reasonable and efficient in the smelting process, so that the phenomenon of over oxidation of a molten metal bath is avoided; the oxygen lance oxygen supply flow can be finely adjusted according to the slag overflowing condition at the furnace door.
6. The method according to claim 1, wherein in the step 4, the carbon powder spraying rate is basically constant in the smelting process, and the carbon powder spraying is completed by a furnace door carbon gun and a furnace wall carbon gun.
7. The method according to claim 1, wherein the step 5 specifically comprises:
step 51: beginning to smelt for 22-25min, taking a steel sample for first component detection, and determining the average carbon content of the mixed scrap steel according to the first component detection result;
step 52: and taking a steel sample before tapping at the smelting end point for secondary component detection, and verifying the validity of the average carbon content of the mixed steel scrap according to the secondary component detection result.
8. The method according to claim 7, wherein the step 51 of determining the average carbon content of the mixed scrap according to the first component detection result is performed according to the following formula:
Figure FDA0003492904470000011
Figure FDA0003492904470000021
wherein:
Mscrap Steel 1The amount of scrap steel, kg, added from the beginning of smelting to the first sampling;
[％Cscrap steel]-average carbon content of mixed scrap,%;
Mcarbon ball-the amount of carbon spheres added, kg;
Mcarbon powder 1The amount of the carbon powder added from the beginning of smelting to the first sampling period is kg;
Mretained steel-leaving the mass of steel in kg;
[％Cretained steel]-leaving steel carbon content,%;
[％Csample 1]-sampling carbon content,%;
Δ1O2-oxygen consumption, Nm, from the start of the smelting to the sampling3；
f-Metal yield,%;
Figure FDA0003492904470000022
-oxygen utilization for decarburization,%;
Figure FDA0003492904470000023
1kg of oxygen consumed by the oxidation of carbon, Nm3/kg。
9. The method according to claim 7, characterized in that, in said step 52, the tapping temperature at the end of the smelting: t is more than 1580 ℃.
10. The method of claim 7, wherein the step 52 of verifying the validity of the average carbon content of the mixed scrap steel according to the second component detection result is performed according to the following formula:
Figure FDA0003492904470000024
wherein:
Mscrap Steel 1The amount of scrap steel, kg, added from the beginning of smelting to the first sampling;
[％Cscrap steel]-average carbon content of mixed scrap,%;
Mretained steel-leaving the mass of steel in kg;
[％Csample 1]-sampling carbon content,%;
Mscrap Steel 2-the amount of scrap steel, kg, added during the period from the primary sampling to the secondary sampling;
Mcarbon powder 2-the amount of carbon powder added during the period from the first sampling to the second sampling, kg;
[％Csample 2]-carbon content of secondary sample,%;
Δ2O2oxygen consumption, Nm, from primary to secondary sampling3；
f-Metal yield,%;
Figure FDA0003492904470000031
-oxygen utilization for decarburization,%;
Figure FDA0003492904470000032
1kg of oxygen consumed by the oxidation of carbon, Nm3/kg。
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