阅读说明：本技术 基于电炉除尘灰的高炉铁水脱碳方法 (Blast furnace molten iron decarburization method based on electric furnace dust removal ash ) 是由 张永杰 陈立军 孙国伟 陈国军 王明月 于 2020-06-30 设计创作，主要内容包括：本发明涉及一种基于电炉除尘灰的高炉铁水脱碳方法,其步骤依次包括：准备脱碳剂基料,脱碳剂基料的原料包括电炉除尘灰；将脱碳剂基料与无机粘结剂混合作为混合料,再与水混合后制成小块并烘干得到块状脱碳剂,所述无机粘结剂占混合料重量的5～8%；将块状脱碳剂装填至排空的鱼雷罐车内底部,块状脱碳剂的用量为灌装至鱼雷罐车的铁水重量的3～6%,鱼雷罐车余热对块状脱碳剂进行预热；将铁水倒灌至鱼雷罐车内,铁水温度为1330～1500℃,铁水与块状脱碳剂接触并氧化反应进行脱碳处理。本发明操作简便、易于实现,从根源上解决石墨粉尘污染问题,在确保脱碳效果的同时能有效利用废弃物资源,投资少、成本低。(The invention relates to a blast furnace molten iron decarburization method based on electric furnace fly ash, which sequentially comprises the following steps: preparing a decarbonizing agent base stock, wherein the raw material of the decarbonizing agent base stock comprises electric furnace dedusting ash; mixing a decarbonizer base material with an inorganic binder to obtain a mixture, mixing the mixture with water to obtain small blocks, and drying the small blocks to obtain a blocky decarbonizer, wherein the inorganic binder accounts for 5-8% of the weight of the mixture; filling a blocky decarbonizer to the bottom in an evacuated torpedo ladle car, wherein the using amount of the blocky decarbonizer is 3-6% of the weight of molten iron filled in the torpedo ladle car, and preheating the blocky decarbonizer by using the waste heat of the torpedo ladle car; and pouring the molten iron into the torpedo ladle car, wherein the temperature of the molten iron is 1330-1500 ℃, and the molten iron is contacted with the blocky decarbonizing agent and is subjected to oxidation reaction for decarbonization treatment. The method has simple and convenient operation and easy realization, radically solves the problem of graphite dust pollution, can effectively utilize waste resources while ensuring the decarburization effect, and has less investment and low cost.)

1. A blast furnace molten iron decarburization method based on electric furnace fly ash is characterized in that: the method comprises the following steps:

preparing a decarbonizing agent base stock, wherein the raw material of the decarbonizing agent base stock comprises electric furnace dedusting ash;

step two, mixing the base material of the decarbonizing agent with an inorganic binder to obtain a mixture, mixing the mixture with water to prepare small blocks, and drying the small blocks to obtain a blocky decarbonizing agent, wherein the inorganic binder accounts for 5-8% of the weight of the mixture;

step three, filling a blocky decarbonizer to the bottom in the emptied torpedo ladle car, wherein the using amount of the blocky decarbonizer is 3-6% of the weight of the molten iron filled in the torpedo ladle car, and preheating the blocky decarbonizer by the waste heat of the torpedo ladle car;

and step four, pouring the molten iron into the torpedo ladle car, wherein the temperature of the molten iron is 1330-1500 ℃, and the molten iron is contacted with the blocky decarbonizing agent and is subjected to oxidation reaction for decarbonization treatment.

2. The method for decarbonizing blast furnace molten iron based on electric furnace dust removal according to claim 1, characterized in that: in the first step, the electric furnace dust removal ash is roasted to prepare a decarbonizer base material, and the roasting conditions are as follows: roasting in air at 800-1000 ℃ for 1-3 hours.

3. The method for decarbonizing blast furnace molten iron based on electric furnace dust removal according to claim 1, characterized in that: in the first step, the raw materials of the base material of the decarbonizer also comprise iron ore concentrate powder, the electric furnace dust removal ash and the iron ore concentrate powder are blended, the weight percentage of the electric furnace dust removal ash is 1-99%, the rest is the iron ore concentrate powder, and the TFe content in the iron ore concentrate powder is 50-67%.

4. The method for decarbonizing blast furnace molten iron based on electric furnace dust removal according to claim 1, characterized in that: in the first step, the base material of the decarbonizer also comprises steel rolling iron scale, the electric furnace dust removal ash and the steel rolling iron scale are blended, the electric furnace dust removal ash accounts for 1-99% by weight, and the balance is the steel rolling iron scale.

5. The method for decarbonizing blast furnace molten iron based on electric furnace dust removal according to claim 1, characterized in that: in the first step, the raw materials of the base material of the decarbonizer also comprise iron concentrate powder and steel rolling iron scale, and the dedusting ash of the electric furnace, the iron concentrate powder and the steel rolling iron scale are blended, wherein the corresponding weight percentages are 50-70%, 10-30% and 10-30%.

6. The method for decarbonizing blast furnace molten iron based on electric furnace dust according to any one of claims 3 to 5, characterized in that: roasting treatment is carried out before blending of the electric furnace dust removal ash, and roasting conditions are as follows: roasting in air at 800-1000 ℃ for 1-3 hours.

7. The method for decarbonizing blast furnace molten iron based on electric furnace dust removal according to claim 1, characterized in that: in the second step, the mixture and water are fully mixed for pulping and pressed into small blocks, or the mixture and water are fully mixed and directly pelletized to obtain spherical small blocks.

8. The method for decarbonizing blast furnace molten iron based on electric furnace dust according to claim 1 or 7, characterized in that: in the second step, the block size of the block-shaped decarbonizer is 0.3-5 cm,

the method for decarbonizing blast furnace molten iron based on electric furnace dust removal according to claim 1, characterized in that: in the fourth step, when the blocky decarbonizer is mixed with molten iron for decarbonization, the temperature of the molten iron is 1400-1500 ℃.

9. The method for decarbonizing blast furnace molten iron based on electric furnace dust removal according to claim 1, characterized in that: in the second step, part of the base material of the decarbonizer is made into powdery decarbonizer; in the third step, a powdery decarbonizing agent is paved in advance in an iron runner connecting a blast furnace iron nozzle and a torpedo tank car; in the fourth step, the molten iron contacts with the powdery decarbonizer when flowing through the molten iron runner and is subjected to oxidation reaction for pre-decarbonization treatment.

Technical Field

The invention relates to a molten iron decarburization technology in a steelmaking process, in particular to a blast furnace molten iron decarburization method based on electric furnace dust removal.

Background

On the basis that the current steel production process is basically mature and stable, the technology of continuously improving an interface between equipment is an effective measure for optimizing production indexes, wherein the iron-steel interface between a blast furnace and a converter (a mixer furnace) is particularly important, namely molten iron (the temperature is about 1500 ℃) discharged from the blast furnace of a steel plant is filled into a torpedo tank car, and then the molten iron is transported into the mixer furnace or a converter ladle of the steel plant through the torpedo tank car, in the process, the temperature of the molten iron is sharply reduced to about 1320 ℃ due to heat dissipation loss, the solubility of carbon in the molten iron is greatly reduced due to temperature reduction of more than 100 ℃, a large amount of precipitation is caused, a large amount of high-temperature carbon powder is generated, and even a large amount of flake graphite is seen, and the main components of the smoke are carbon and iron and the content is more than 70% -80% through detection and analysis. It has been found that the saturated solubility of carbon decreases by 0.24% on average for every 100 ℃ drop in the temperature of the molten iron, i.e. about 2.4kg of carbon is precipitated from 1 ton of molten iron, whereby several tens of tons of carbon-containing dust are generated at the iron-steel interface for a thousand tons of molten iron per day. Not only does this waste a large amount of carbon, iron resources, but also has influenced atmospheric quality, has caused great injury to equipment and human body, for example the flake graphite dust falls and is easy to take place to skid when driving rail surface, again like partial carbon forms Fe with iron₃When C is separated out, the influence on the electrical equipment with the magnetic field in the production field is great, and the heat dissipation and insulation performance and the service life of the electrical equipment are seriously influenced. In addition, the graphite dust is smooth and easy to adhere, and skin itch, red swelling and other symptoms are easy to cause when the graphite dust contacts the skin of a human body.

There are several current approaches to solving this problem: firstly, an air draft dust removal method is adopted to purify air; secondly, the external heat insulation structure of the torpedo tank car is improved to reduce the heat loss of the molten iron in the tank, so that the temperature drop of the molten iron in the transportation process is reduced; thirdly, the torpedo tank car adopts a capping mode, so that the heat loss of molten iron is reduced. The first method is restricted by process operation, the dust removal smoke hood conflicts with the operation of other equipment, the equipment is difficult to arrange, the maintenance and operation cost is high, the smoke and dust complementary effect is not good, and the treatment of symptoms and root causes is not good. The latter two methods have certain effect, but still cannot avoid the generation of a large amount of graphite dust because the carbon-saturated molten iron from the blast furnace inevitably generates carbon precipitation in the temperature reduction process.

Therefore, there is a need to solve the problem of reducing graphite dust contamination by reducing the carbon content in the molten iron based on the prior art. Therefore, when a certain iron and steel enterprise carries out a carbon reduction test on a molten iron sample, iron concentrate powder such as Yunnan beach ore, Brazil powder, premixed powder, sintered return ore and the like is used as a decarbonizer, the decarbonizer is filled into a 25kg woven bag, and when molten iron is discharged from a blast furnace, the mineral powder is manually added into an iron runner behind a small dam in front of the blast furnace. Although the test method can realize the carbon reduction of the molten iron, the following problems still exist: firstly, the iron ore concentrate powder is used as a decarbonizer, so the cost is higher; secondly, after the Yunnan beach mineral powder at room temperature is directly added into the molten iron, the temperature of the molten iron is reduced by about 20 ℃, the heat loss is large, and the generation of carbon-containing dust is aggravated; thirdly, when the iron concentrate powder is used on site, the Yunnan beach mineral powder packaged by the woven bag is directly added into the iron runner manually when the molten iron is discharged from the blast furnace, so that the molten iron is easy to splash and the material is lost, and potential safety hazards exist.

In addition, the electric furnace dust is collected by the trap, the flue and the bag type dust collector during electric furnace steelmaking, and accounts for about 1-2% of the charging amount of furnace burden produced by electric furnace steelmaking. Generally speaking, the total iron content of TFe in the electric furnace dust removal ash is 43.17-46.82%, the weight percentage of FeO is 15.00-17.00%, and Fe₂O₃The weight percentage is 45.00-48.00%. The electric furnace dust also contains a large amount of elements which are harmful to the production of the blast furnace, such as zinc, potassium and sodium oxides, which can cause the furnace wall of the blast furnace to form nodules, worsen the furnace condition of the blast furnace and influence the smooth operation and the furnace life of the blast furnace, and lead is gathered in a hearth of the blast furnace to influence the service life of the blast furnace and have potential safety hazards. Therefore, the electric furnace dust cannot be directly added into a blast furnace for use, and is a solid waste in metallurgical industry which is difficult to recycle. The domestic treatment of the electric furnace dust is mostly realized by adopting a landfill or abandonment method, which causes pollution to the environment and wastes metal resources, and the iron and zinc extraction treatment is also carried out on the electric furnace dust by adopting the processes of leaching, wet method, pyrogenic method and the like, but the operation difficulty is high, and the dust is transported backwardsSecondary pollution in the process, high investment in building plants in different places and the like, and the investment of the pyrogenic process, the wet process and the combined treatment process is large and the cost is high.

Disclosure of Invention

The invention aims to provide a blast furnace molten iron decarburization method based on electric furnace dedusting ash, which is characterized in that the electric furnace dedusting ash is adopted as a main raw material of a decarburization agent base material to prepare a decarburization agent, and the decarburization agent is applied to molten iron in the process that the blast furnace molten iron enters a torpedo car, so that iron oxide in the decarburization agent and carbon in the blast furnace molten iron are subjected to oxidation reaction, and molten iron decarburization is realized.

The invention is realized by the following steps:

a blast furnace molten iron decarburization method based on electric furnace fly ash comprises the following steps:

preparing a decarbonizing agent base stock, wherein the raw material of the decarbonizing agent base stock comprises electric furnace dedusting ash;

step two, mixing the base material of the decarbonizing agent with an inorganic binder to obtain a mixture, mixing the mixture with water to prepare small blocks, and drying the small blocks to obtain a blocky decarbonizing agent, wherein the inorganic binder accounts for 5-8% of the weight of the mixture;

step three, filling a blocky decarbonizer to the bottom in the emptied torpedo ladle car, wherein the using amount of the blocky decarbonizer is 3-6% of the weight of the molten iron filled in the torpedo ladle car, and preheating the blocky decarbonizer by the waste heat of the torpedo ladle car;

and step four, pouring the molten iron into the torpedo ladle car, wherein the temperature of the molten iron is 1330-1500 ℃, and the molten iron is contacted with the blocky decarbonizing agent and is subjected to oxidation reaction for decarbonization treatment.

In the first step, the electric furnace dust removal ash is roasted to prepare a decarbonizer base material, and the roasting conditions are as follows: roasting in air at 800-1000 ℃ for 1-3 hours.

In the first step, the raw materials of the base material of the decarbonizer also comprise iron ore concentrate powder, the electric furnace dust removal ash and the iron ore concentrate powder are blended, the weight percentage of the electric furnace dust removal ash is 1-99%, the rest is the iron ore concentrate powder, and the TFe content in the iron ore concentrate powder is 50-67%.

In the first step, the base material of the decarbonizer also comprises steel rolling iron scale, the electric furnace dust removal ash and the steel rolling iron scale are blended, the electric furnace dust removal ash accounts for 1-99% by weight, and the balance is the steel rolling iron scale.

In the first step, the raw materials of the base material of the decarbonizer also comprise iron concentrate powder and steel rolling iron scale, and the dedusting ash of the electric furnace, the iron concentrate powder and the steel rolling iron scale are blended, wherein the corresponding weight percentages are 50-70%, 10-30% and 10-30%.

Roasting treatment is carried out before blending of the electric furnace dust removal ash, and roasting conditions are as follows: roasting in air at 800-1000 ℃ for 1-3 hours.

In the second step, the mixture and water are fully mixed for pulping and pressed into small blocks, or the mixture and water are fully mixed and directly pelletized to obtain spherical small blocks.

In the second step, the block size of the block-shaped decarbonizer is 0.3-5 cm,

in the fourth step, when the blocky decarbonizer is mixed with molten iron for decarbonization, the temperature of the molten iron is 1400-1500 ℃.

In the second step, part of the base material of the decarbonizer is made into powdery decarbonizer; in the third step, a powdery decarbonizing agent is paved in advance in an iron runner connecting a blast furnace iron nozzle and a torpedo tank car; in the fourth step, the molten iron contacts with the powdery decarbonizer when flowing through the molten iron runner and is subjected to oxidation reaction for pre-decarbonization treatment.

The invention relates to a blast furnace molten iron decarburization method based on electric furnace dedusting ash, which comprises the steps of firstly, adding a decarburization agent taking the electric furnace dedusting ash as a decarburization agent or taking the electric furnace dedusting ash as a base material into molten iron discharged from a blast furnace, and carrying out oxidation-reduction reaction between the decarburization agent and carbon in the molten iron at a high temperature of 1330-1500 ℃ to effectively remove carbon in the molten iron, so as to realize pretreatment decarburization of the discharged iron from the blast furnace, radically solve the pollution problem of graphite dust in the molten iron inversion link of iron and steel enterprises. In particular, Fe of electric furnace dust₂O₃The content reaches more than about 45 percent due to Fe₂O₃Has strong oxidizability at high temperature, and can oxidize C contained in molten iron into CO or CO₂And the iron element in the electric furnace dust is efficiently recovered. Furthermore, the fly ash of the electric furnace subjected to the aerobic roasting has a carbon content of substantially 0 and contains Fe₂O₃Can reach more than 64 percent, further improves the decarburization efficiency of the electric furnace dust removal ash, and can comprehensively improve the proportion of iron oxide in the mixture and improve the oxidation decarburization efficiency of the decarburization agent by blending with iron concentrate powder or steel rolling iron scale.

Secondly, in the application mode of the decarbonizing agent, part of base materials of the decarbonizing agent can be made into powdery decarbonizing agent and is paved in a molten iron flow channel (molten iron ditch) connected between a blast furnace and a torpedo car in advance to pre-decarbonize the flowing molten iron, and the molten iron flows through the molten iron ditch in sequence in a flowing state and can fully contact with the powdery decarbonizing agent and react for decarbonization. Meanwhile, the decarbonizer base material is made into small blocks of blocky decarbonizer and placed in the torpedo car with emptied molten iron, in the process that the torpedo car returns to an iron-making plant from the steel-making plant, the blocky decarbonizer is preheated by the waste heat of the torpedo car, so that the blocky decarbonizer is raised to 800-1000 ℃ from normal temperature, the heat loss generated when the blocky decarbonizer is contacted with high-temperature molten iron (generally 1480 ℃) is reduced, the phenomenon of carbon precipitation caused by excessive temperature drop is avoided, and the blocky decarbonizer is impacted when the blast furnace molten iron is poured into the torpedo car, so that the blocky decarbonizer and the molten iron are fully mixed and contacted, the carbon in the molten iron is removed, and stirring operation is not needed. In addition, the electric furnace dust removal ash is pressed into blocks to be made into the blocky decarbonizer, so that the molten iron splashing and the material loss are reduced, and the utilization rate is effectively improved.

Compared with the prior art, the invention has the following beneficial effects: simple operation and easy realization, radically solves the problem of graphite dust pollution, can effectively utilize waste resources while ensuring the decarburization effect, and has less investment and low cost.

Detailed Description

The present invention will be further described with reference to the following specific examples.

The invention relates to a blast furnace molten iron decarburization method based on electric furnace dedusting ash, which is characterized in that a decarburization agent which takes the electric furnace dedusting ash as a main raw material is added in advance in a torpedo ladle car, and the blast furnace molten iron and the decarburization agent are subjected to oxidation reaction for decarburization treatment in the process of filling the molten iron discharged from a blast furnace into the torpedo ladle car, so that the generation of carbon dust is reduced radically. The method specifically comprises the following steps:

step one, preparing a decarbonizer base material, wherein the raw material of the decarbonizer base material mainly comprises electric furnace dust which can be used independently and directly or can be used after being blended with iron concentrate powder and/or steel rolling iron scale to obtain the decarbonizer base material.

The TFe total iron content of the electric furnace dust removal ash is 43.17-46.82%, and the electric furnace dust removal ash comprises the following chemical components in percentage by weight: fe₂O₃：45.00~48.00%、FeO：15.00~17.00%、S：0.320~0.510%、SiO₂：2.50~4.50%、Al₂O₃：0.50~0.90%、CaO：9.00~11.00%、MgO：3.00~4.00%、MnO：1.0~2.0%、P₂O₅: 0.250 to 0.350%, C: 1.50-1.80%, ZnO: 6.00-8.00%, and the balance of impurities: 3.50 to 5.50 percent.

It can be seen that the ash removed from the electric furnace contains a certain amount of carbon which can be removed by calcination before it is used as a base for decarburization, preferably under the following calcination conditions: roasting in the air at 800-1000 ℃ for 1-3 hours, wherein the carbon content of the roasted electric furnace dust is close to 0, and basically all ferrous iron is converted into ferric iron, so that better oxidizability can be provided.

When the raw material of the base material of the decarbonizer is selected, electric furnace fly ash which is difficult to recycle is selected, the electric furnace fly ash is used as the base material of the decarbonizer after roasting or not, or the electric furnace fly ash is mixed with at least one of iron concentrate powder and steel rolling iron scale in proportion to form the base material of the decarbonizer after roasting or not. Specifically, the manner of composing the base material of the decarbonizer includes, but is not limited to, the following: 1) directly taking electric furnace dust-removing ash as a base material of a decarbonizer; 2) roasting the electric furnace dust to prepare a decarbonizer base material; 3) directly mixing electric furnace dust removal ash with iron concentrate powder to prepare a decarbonizer base material; 4) the electric furnace dust is directly mixed with steel rolling iron scale to prepare a decarbonizer base material; 5) directly mixing electric furnace dust with iron concentrate powder and steel rolling iron scale to prepare a decarbonizer base material; 6) roasting the electric furnace fly ash, and mixing the roasted electric furnace fly ash with iron concentrate powder to prepare a decarbonizer base material; 7) roasting the electric furnace dust removal ash, and mixing the roasted electric furnace dust removal ash with steel rolling iron scale to prepare a decarbonizer base material; 8) the electric furnace dust removal ash is roasted and then mixed with iron concentrate powder and steel rolling iron scale to prepare a decarbonizer base material.

When the electric furnace dust removal ash and the iron concentrate powder are blended to form the decarbonizer base material, the weight percentage of the electric furnace dust removal ash is 1-99%, and the rest is the iron concentrate powder, wherein the TFe total iron content in the iron concentrate powder is 50-67%, for example: the weight percentage of the electric furnace dust removal ash can be 99%, 80%, 75% or 50%, and the rest is iron concentrate powder. When the electric furnace dust removal ash and the steel rolling iron scale are blended to form the decarbonizer base material, the weight percentage of the electric furnace dust removal ash is 1-99%, and the rest is the steel rolling iron scale, preferably, the weight percentage of the electric furnace dust removal ash is 50-99%, for example: the weight percentage of the electric furnace dust removal ash can be 99%, 80%, 75% or 50%, and the rest is iron concentrate powder. When the electric furnace dust removal ash, the iron concentrate powder and the steel rolling iron scale are blended to form the decarbonizer base material, the corresponding weight percentage is 50-70%, 10-30% and 10-30%.

And step two, the base material of the decarbonizer is made into small blocks, which aims to increase the particle size of the decarbonizer when the decarbonizer is added into the blast furnace molten iron and prevent the loss and safety problems caused by high-temperature splashing. Although the powdery decarbonizer can also be directly mixed with molten iron from a blast furnace, if the adding mode is improper, splashing is easy to generate, certain material loss is caused, and the blocky decarbonizer can reduce the splashing. The specific shape of the block is not limited, and can be a regular cylinder, a rectangular body, an ellipsoid, a sphere or an irregular three-dimensional shape, and the size of the block can be 0.3-5 cm. Specifically, a decarbonizer base material and an inorganic binder are mixed to be used as a mixture, then the mixture is fully mixed with a proper amount of water for pulping, pressed into small blocks and dried to obtain a blocky decarbonizer, or the mixture is fully mixed with a proper amount of water for direct pelletizing and dried to obtain a blocky decarbonizer in a small block spherical shape, wherein the inorganic binder accounts for 5-8% of the weight of the mixture, preferably, the inorganic binder is bentonite, and the drying conditions are as follows: the drying temperature is 110-120 ℃, and the drying time is 3-5 hours.

In addition, part of the base material of the decarbonizer can be made into powdery decarbonizer which is paved in the molten iron ditch to carry out pre-decarbonization treatment on the molten iron. Wherein, the electric furnace dust removal ash and the iron ore concentrate powder are powder materials which can be directly used as a powdery decarbonizer, and the rolled steel scale is not easy to be made into powder materials, such as the rolled steel scale with small granularity or in a flake shape, and can also be directly laid in an iron runner.

And step three, filling the blocky decarbonizing agent to the bottom in the emptied torpedo ladle car, and preheating the blocky decarbonizing agent by means of the waste heat of the torpedo ladle car, wherein the using amount of the blocky decarbonizing agent is 3-6% of the weight of the molten iron filled in the torpedo ladle car. In addition, powdery decarbonizing agent can be paved in the molten iron ditch connecting the blast furnace molten iron nozzle and the torpedo tank car in advance.

First, the most important way of applying the decarburizing agent is: after molten iron is poured into a converter or a ladle of a steel plant from a torpedo car, the block-shaped decarbonizer is filled to the bottom of the torpedo car, and the block-shaped decarbonizer is preheated in the process that the torpedo car returns to the steel plant from the steel plant, wherein the use amount of the block-shaped decarbonizer is 3-6% of the weight of the molten iron to be poured into the torpedo car. If the consumption of the decarbonizer is too much, the heat loss of molten iron is too large, the temperature drop is too fast, carbon precipitation is aggravated, and the decarbonizer can not react completely in a limited time; if the amount of the decarbonizer is too small, the carbon reduction amount of the blast furnace molten iron cannot be ensured to meet the expectation. Secondly, still can carry out the decarbonization in advance before the blast furnace molten iron flows through the iron runner and gets into the torpedo tank car, lay powdery decarbonizer in the iron runner of connecting blast furnace molten iron mouth and torpedo tank car in advance promptly, make the molten iron flow through powdery decarbonizer and react and realize the decarbonization, such application mode neither can appear a large amount of splash, has played partial decarbonization effect to the blast furnace molten iron that flows through, has also reduced the work load of carrying out briquetting stoving to whole decarbonizer base materials.

And step four, pouring the molten iron from a blast furnace molten iron port into the torpedo car through a molten iron ditch, and contacting the molten iron with a decarbonizing agent and carrying out an oxidation reaction to carry out decarbonization treatment. Specifically, molten iron can contact with a powdery decarbonizer laid in advance and carry out oxidation reaction when flowing through the molten iron ditch, and the molten iron can contact with a blocky decarbonizer and carry out oxidation reaction when entering the torpedo ladle car. When the massive decarbonizing agent is in contact reaction with molten iron for decarbonization, the temperature of the molten iron is 1330-1500 ℃, and particularly, a good decarbonization effect can be realized when the temperature of the molten iron is 1400-1500 ℃, because if the temperature of the molten iron is lower than 1400 ℃, the reaction speed is slow, the corresponding reaction time is prolonged, and partial residue and incomplete reaction of the decarbonizing agent can be caused.

Example 1

The electric furnace dust removal ash is used as a base material of the decarbonizer and is mixed with blast furnace molten iron to realize decarbonization. Table 1 lists the TFe total iron content, chemical composition and weight percent thereof for the furnace dust sample of example 1 as follows:

the particle size of the electric furnace dust is 10-50 microns, a certain amount of electric furnace dust is mixed with an inorganic binder to serve as a mixture, then the mixture is fully mixed with water to be uniformly prepared into pulp and pressed into blocks, the blocks are dried at the temperature of 110-120 ℃ for 3-5 hours, and a cylindrical block-shaped decarbonizer is obtained, wherein the diameter of the cylindrical block-shaped decarbonizer is 1cm, the height of the cylindrical block-shaped decarbonizer is 1.5cm, the inorganic binder is bentonite, and the bentonite accounts for 5% of the weight of the mixture.

Sampling from a steel plant, slightly different components exist in each iron block sample (about 500g in weight), in order to enable the detection result to be more accurate, each sample is detected for three times, the average value of the three times is taken, and the carbon content in the iron block sample is repeatedly detected in each experiment, wherein the average content of Si and Mn in the iron block sample is 0.28 percent and 0.20 percent respectively. In this embodiment, the influence of different amounts of decarburizing agents on the decarburization effect of molten iron is studied, specifically, 3%, 4%, and 5% of electric furnace dedusting ash block-shaped decarburizing agents based on the weight of molten iron are respectively added into molten iron, and the temperature of molten iron is kept at 1450 ℃. Table 2 lists the results of the carbon content testing of the iron nugget samples of example 1, as follows:

as can be seen from Table 2, the amount of carbon reduction in molten iron showed a gradually increasing tendency with increasing amounts of the decarbonizing agent, and had a significant effect on decarburization. Meanwhile, 3% of Yunnan beach ore is adopted to realize about 0.30% of carbon reduction amount at the same experiment temperature with the prior art, electric furnace dust removal ash is used as a decarbonizing agent in the embodiment, and the decarbonizing agent is subjected to briquetting treatment, so that the loss caused by molten iron splashing is reduced, the effective utilization rate is improved, and the decarbonizing effect equivalent to that of the prior art can be kept.

Example 2

The electric furnace dust removal ash is used as a base material of the decarbonizer and is mixed with blast furnace molten iron to realize decarbonization. The chemical composition, briquetting specification and briquetting step of the electric furnace dust removal ash in the present example were all the same as those of the electric furnace dust removal ash in example 1, and the specification and detection method of the iron nugget sample were all the same as those of example 1. In this embodiment, the influence of the dedusting ash decarbonizer for the electric furnace on the decarburization effect of molten iron under different molten iron temperature conditions is studied, specifically, the molten iron temperatures for the decarburization reaction are respectively 1330 ℃, 1390 ℃ and 1450 ℃, and in each group of temperature experiment, the usage amount of the dedusting ash for the electric furnace is 4% of the weight of the molten iron, and table 3 lists the experimental results of the carbon content detection of the iron block sample of example 2, as follows:

as can be seen from Table 3, in the case where the amount of the decarburization agent was constant, the relationship between the amount of carbon reduction and the temperature of molten iron during the decarburization reaction was small, and the amount of carbon reduction at 1330 ℃ was close to that at 1450 ℃. Thus, the temperature hardly affected the decarburization effect, and the amount of carbon reduction was determined by the amount of the decarburization agent in combination with the results of the experiment in example 1. From the comprehensive consideration of considering complete reaction and cost saving, when the electric furnace dust removal ash is used as the base material of the decarbonizer and the dosage of the decarbonizer is 4 percent, the carbon reduction of the molten iron can reach more than 0.38 percent.

Example 3

The base material of the decarburization agent includes electric furnace fly ash and iron concentrate powder, and the electric furnace fly ash in this example is the same as that in example 1. The electric furnace dust removal ash and iron concentrate powder (Brazilian iron concentrate powder) are 80 percent by weight: 20, mixing the mixture with an inorganic binder to obtain a mixture, fully and uniformly mixing the mixture with water to prepare slurry, pressing the slurry into blocks, and drying the blocks at the temperature of 110-120 ℃ for 3-5 hours to obtain the cylindrical blocky decarbonizer, wherein the diameter of the cylindrical blocky decarbonizer is 1cm, and the height of the cylindrical blocky decarbonizer is 1.5cm, and the inorganic binder is bentonite accounting for 5% of the weight of the mixture. Table 4 lists the TFe content, chemical composition and weight percent of the iron concentrate fines of example 3, as follows:

in this embodiment, the influence of different amounts of decarburizing agents on the decarburization effect of molten iron is studied, specifically, 3% and 4% of block-shaped decarburizing agents based on the weight of molten iron are respectively added into molten iron, and the temperature of the molten iron is kept at 1450 ℃. The specification and the detection method of the iron nugget sample were the same as those of example 1. Table 5 lists the results of the carbon content testing of the iron nugget samples of example 3, as follows:

as can be seen from Table 3, the ideal carbon reduction effect can be obtained by using the precipitator dust of the electric furnace and the iron ore concentrate powder as the base materials of the decarbonizer, and when the dosage of the decarbonizer is 3%, the carbon reduction of the molten iron can reach 0.33%.

Example 4

The electric furnace dust used in this example was the same as that used in example 1, using the same as the decarburization base. Aerobic roasting is carried out on the electric furnace dust removal ash firstly, and the specific roasting conditions are as follows: roasting in air at 800-1000 deg.c for 1-3 hr, and removing Fe from the dust in electric furnace₂O₃The content is about 64.4%. The same briquette specifications and proportions as in example 1 were then usedAnd (3) briquetting to obtain the blocky decarbonizer.

In this example, the influence of different amounts of decarburizing agents on the decarburization effect of molten iron was studied, specifically, 3%, 4%, and 5% of block-shaped decarburizing agents based on the weight of molten iron were respectively added to molten iron, and the temperature of molten iron was maintained at 1450 ℃. The specification and the detection method of the iron nugget sample were the same as those of example 1. Table 6 lists the results of the carbon content testing of the iron nugget sample of example 4, as follows:

as can be seen from Table 6, the roasted electric furnace dust removed as the base material of the decarburization agent provided a better carbon reduction effect than the test result of example 1, and the carbon reduction of the molten iron was 0.33% when the amount of the decarburization agent was 3%. Thus, the electric furnace dust-removing ash contains Fe after aerobic roasting₂O₃The content is increased, and the oxidation decarburization efficiency of the decarburization agent can be further improved.

Example 5

The base material of the decarburization agent comprises electric furnace dust and steel rolling iron scale, and the electric furnace dust in the embodiment is the same as that in the embodiment 1. The electric furnace dust removal ash and the steel rolling iron scale are 80 percent by weight: 20, mixing the mixture with an inorganic binder to obtain a mixture, fully mixing the mixture with water, pelletizing the mixture by a disc pelletizer, and drying the mixture to obtain a spherical blocky decarbonizer with the diameter of 2cm, wherein the inorganic binder is bentonite, and the bentonite accounts for 5 percent of the weight of the mixture. The steel rolling iron oxide scale is a metallic iron oxide attached to the surface and formed when a billet is processed in a heating or hot rolling state, the thickness of the steel rolling iron oxide scale is about 5-15 micrometers, and the steel rolling iron oxide scale comprises the following main chemical components in percentage by weight: fe₂O₃：36%、FeO：62%。

In this embodiment, the influence of different amounts of decarburizing agents on the decarburization effect of molten iron is studied, specifically, 3% and 4% of block-shaped decarburizing agents based on the weight of molten iron are respectively added into molten iron, and the temperature of the molten iron is kept at 1450 ℃. The specification and the detection method of the iron nugget sample were the same as those of example 1. Table 7 lists the results of the carbon content testing of the iron nugget samples of example 5, as follows:

as can be seen from Table 7, the blending of the electric furnace dust and the steel rolling iron scale as the base materials of the decarbonizer can achieve a very ideal carbon reduction effect, when the dosage of the decarbonizer is 3%, the carbon reduction amount of the molten iron can reach 0.32%, and the high-efficiency recycling of the iron in the electric furnace dust and the steel rolling iron scale is realized. Therefore, the decarbonizer obtained by blending the electric furnace dust removal ash and the steel rolling iron scale as the decarbonizer base material can effectively reduce graphite dust generated in the molten iron inversion link and can effectively recycle iron elements in the steel rolling iron scale.

Example 6

The base material of the decarburization agent includes electric furnace fly ash and iron concentrate powder, and the electric furnace fly ash in this example is the same as that in example 1. Aerobic roasting is carried out on the electric furnace dust removal ash firstly, and the specific roasting conditions are as follows: roasting in air at 800-1000 deg.c for 1-3 hr, and removing Fe from the dust in electric furnace₂O₃The content is about 64.4%. The same iron ore concentrate powder (brazilian iron ore concentrate powder) as in example 3 was used, and the roasted electric furnace fly ash and the iron ore concentrate powder were mixed in a weight ratio of 80: 20, mixing the mixture with an inorganic binder to obtain a mixture, fully and uniformly mixing the mixture with water to prepare slurry, pressing the slurry into blocks, and drying the blocks at the temperature of 110-120 ℃ for 3-5 hours to obtain the cylindrical blocky decarbonizer, wherein the diameter of the cylindrical blocky decarbonizer is 1cm, and the height of the cylindrical blocky decarbonizer is 1.5cm, and the inorganic binder is bentonite accounting for 5% of the weight of the mixture.

In this embodiment, the influence of different amounts of decarburizing agents on the decarburization effect of molten iron is studied, specifically, 3% and 4% of block-shaped decarburizing agents based on the weight of molten iron are respectively added into molten iron, and the temperature of the molten iron is kept at 1450 ℃. The specification and the detection method of the iron nugget sample were the same as those of example 1. Table 8 lists the results of the carbon content testing of the iron nugget samples of example 6, as follows:

as can be seen from Table 8, the decarburization agent obtained by blending the baked electric furnace dust with the iron ore concentrate powder as the decarburization base material in this example is slightly higher in decarburization efficiency than the decarburization agent obtained by blending the unbaked electric furnace dust with the iron ore concentrate powder as the decarburization base material in example 3 under the same conditions.

Example 7

The base material of the decarburization agent comprises electric furnace dust and steel rolling iron scale, and the electric furnace dust in the embodiment is the same as that in the embodiment 1. Aerobic roasting is carried out on the electric furnace dust removal ash firstly, and the specific roasting conditions are as follows: roasting in air at 800-1000 deg.c for 1-3 hr, and removing Fe from the dust in electric furnace₂O₃The content is about 65.4%. Adopting the same steel rolling iron scale as the embodiment 5, and mixing the baked electric furnace dust removal ash and the steel rolling iron scale according to the weight percentage of 80: 20, mixing the mixture with an inorganic binder to obtain a mixture, fully mixing the mixture with water, pelletizing the mixture by a disc pelletizer, and drying the mixture to obtain a spherical blocky decarbonizer with the diameter of 2cm, wherein the inorganic binder is bentonite, and the bentonite accounts for 5 percent of the weight of the mixture.

In this embodiment, the influence of different amounts of decarburizing agents on the decarburization effect of molten iron is studied, specifically, 3% and 4% of block-shaped decarburizing agents based on the weight of molten iron are respectively added into molten iron, and the temperature of the molten iron is kept at 1450 ℃. The specification and the detection method of the iron nugget sample were the same as those of example 1. Table 9 lists the results of the carbon content testing of the iron nugget samples of example 7, as follows:

as can be seen from Table 9, the decarburization agent obtained by blending the baked electric furnace dust with the rolled steel scales as the decarburization base material in this example has higher decarburization efficiency under the same conditions than the decarburization agent obtained by blending the unbaked electric furnace dust with the rolled steel scales as the decarburization base material in example 5. And compared with the decarbonizer which is obtained by blending the roasted electric furnace dust removal ash and the iron ore concentrate powder as the base material of the decarbonizer in the embodiment 6, the decarbonization efficiency of the two is equivalent under the same condition. However, the decarbonizer obtained by blending the electric furnace dust removal ash and the steel rolling iron scale as the decarbonizer base material not only can realize high-efficiency recycling of the steel rolling iron scale with high iron content, but also can reduce the amount of impurity elements introduced into molten iron.

Example 8

The base material of the decarbonizer comprises electric furnace dust, iron concentrate powder and steel rolling iron scale, and the electric furnace dust in the embodiment is the same as the electric furnace dust in the embodiment 1. The same iron concentrate powder (brazilian iron concentrate powder) as in example 3 and the same steel rolling scale as in example 5 were used, and the dust removed by the electric furnace, the iron concentrate powder and the steel rolling scale were mixed in a weight ratio of 66: 17: 17, mixing the mixture with an inorganic binder to obtain a mixture, fully and uniformly mixing the mixture with water to prepare slurry, pressing the slurry into blocks, and drying the blocks at the temperature of 110-120 ℃ for 3-5 hours to obtain the cylindrical blocky decarbonizer, wherein the diameter of the cylindrical blocky decarbonizer is 1cm, and the height of the cylindrical blocky decarbonizer is 1.5cm, and the inorganic binder is bentonite accounting for 5% of the weight of the mixture. Table 10 lists the results of the carbon content testing of the iron nugget samples of example 8, as follows:

as can be seen from Table 10, the decarburization efficiency of the decarburization agent obtained by blending the electric furnace dust with the iron concentrate powder and the rolled steel scales as the decarburization base material in this example is equivalent to that of the decarburization agent obtained by blending the electric furnace dust with the iron concentrate powder as the decarburization base material in example 3 under the same conditions. However, in this embodiment, the iron scales of the rolled steel with high iron content can be efficiently recycled, and the amount of impurity elements introduced into the molten iron can be reduced.

In the above examples 1 to 8, it was verified in a laboratory that the decarbonizer of each example reacted with blast furnace molten iron, and it was confirmed that the carbon content in the blast furnace molten iron could be reduced, and a large amount of graphite dust generated by the blast furnace molten iron due to temperature drop could be radically reduced, thereby alleviating the dust pollution problem of iron and steel enterprises and reducing the load of dust removal equipment.

When the decarburization agent is used on site in the molten iron inversion link of a steel plant, on the aspect of the application mode of the decarburization agent, firstly, after molten iron is poured into a converter or a ladle of the steel plant from a torpedo car, the blocky decarburization agent is filled to the bottom of the torpedo car, so that in the process that the torpedo car returns to the steel plant from the steel plant, the decarburization agent is preheated by the waste heat of the torpedo car, and the heat loss of the molten iron caused by direct mixing of the decarburization agent and the molten iron of a blast furnace is reduced; secondly, before the blast furnace tapping, a powdery decarbonizing agent is paved in a molten iron groove connecting a molten iron hole from the blast furnace and a torpedo car, so that the molten iron flows through the powdery decarbonizing agent and reacts with each other to realize pre-decarbonization, and the powdery decarbonizing agent can quickly react with the molten iron in the molten iron groove without splashing.

The present invention is not limited to the above embodiments, and any modifications, equivalent replacements, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.