Non-blast-furnace iron manufacturing process using coke oven gas as main heat source for melt separation of waste steel and solid waste

Abstract

The invention discloses a non-blast furnace ironmaking process taking coke oven gas as a main heat source and a reducing agent, which comprises the following steps: uniformly distributing scrap steel, solid waste, coke and a flux from the upper part into a melt separation furnace according to a certain proportion, spraying coke oven gas and hot air into the bottom end of the melt separation furnace through a spray gun, and carrying out combustion, reduction and carburization to generate qualified molten iron; wherein the coke mainly serves as a carburizing source and provides a small part of heat, and the heat and the reducing agent are mainly provided by coke oven gas. Compared with a blast furnace process, the method has the technical advantages that iron ore is not used, the coke is only used as a carburizing agent in a small amount, coke oven gas provides heat and reduction, the whole process is clean and low in carbon emission, and the development route of low-carbon green steel smelting is met.

Description

Technical Field

[0001] The invention belongs to the technical field of non-blast furnace ironmaking in the steel industry, and in particular relates to a non-blast furnace ironmaking process for melting and separating scrap steel and solid waste using coke oven gas as a main heat source. Background Art

[0002] Under the dual carbon background of "carbon peak" and "carbon neutrality", the steel industry, which has huge carbon emissions, urgently needs energy transformation and opens up a green and low-carbon development path. Traditional ironmaking methods mostly use blast furnaces, which have the advantages of high thermal efficiency and large output, but they must use precious coke as the main fuel, resulting in high carbon emissions and costs. In addition, the current high price of imported ore leads to high production costs for steel mills, and there is an urgent need to open up a sustainable supply path for raw materials.

[0003] Scrap steel is an important renewable resource in the steel industry and the only steelmaking raw material that can replace iron ore. According to statistics, using scrap steel to smelt 1 ton of molten steel can save 1.65 tons of high-grade iron ore, and at the same time save 350 kilograms of standard coal, reduce CO2 emissions by 1.6 tons and reduce 4.3 tons of solid waste. Due to the rise in iron ore prices, its share of the cost of each ton of steel billet has increased from 40% to 50%. Therefore, increasing the use of scrap steel is not only of great significance to reducing energy consumption and environmental pollution in the steel industry, thereby achieving green development, but also can reduce the cost of steel enterprises and increase economic benefits. Solid waste Baosteel blast furnace dust removal ash, gas ash, etc., which contain recyclable iron resources, has a good recycling effect.

[0004] Coke oven gas is produced when a coke plant makes coke, and it contains 55-60% H2 and 23%-27% CH4. Coke oven gas has the advantages of high calorific value, fast combustion speed and low pollutant emissions. Coke oven gas is often used for power generation, hydrogen production, methanol synthesis, and combustion and heat generation. These treatment methods lead to serious waste of coke oven gas. At present, coke oven gas is used to smelt molten iron, which can provide both heat source and H2 and CO required for reduction. Therefore, it is very necessary to study the process of melting scrap steel and solid waste ironmaking with coke oven gas. Summary of the invention

[0005] The purpose of the present invention is to provide a non-blast furnace ironmaking process for melting scrap steel and solid waste using coke oven gas as the main heat source, wherein scrap steel, solid waste, coke and flux are evenly distributed from the top to a melting furnace in a certain proportion, and coke oven gas and hot air are sprayed into the bottom of the melting furnace through a spray gun. After combustion, reduction and carburization, qualified molten iron is generated, wherein the coke is mainly used as a carburizing source and provides a small amount of heat, and the heat and reducing agent are mainly provided by the coke oven gas.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] The present invention discloses a non-blast furnace ironmaking process for melting and separating scrap steel and solid waste using coke oven gas as a main heat source, which specifically comprises:

[0008] (1) Making irregular scrap steel and solid waste into blocks with an equivalent diameter of 0.2 to 0.45 m;

[0009] (2) using a material elevator to place scrap steel, solid waste blocks, coke and flux in batches and in layers into a melting furnace, adding scrap steel, solid waste blocks, flux and coke in layers according to type and proportion to melt the molten iron;

[0010] (3) To ensure that the quality of the molten iron is up to standard, the carbon content of the coke is controlled to be not less than 86.0% and the sulfur content is not more than 0.70% by mass;

[0011] (4) In order to ensure the quality of the generated molten iron, magnesite and silica are used as flux; in terms of mass percentage, the CaO content of magnesite is controlled to be no higher than 5.0%, the SiO2 content is no lower than 40.0%, the MgO content is between 0.15 and 0.35, and the SiO2 content of silica is controlled to be no lower than 95.0%;

[0012] (5) The coke oven gas and hot air are mixed and sprayed into the furnace through a mixing nozzle to burn and continuously melt the scrap steel and solid waste to generate molten iron at 1400±20℃, and the molten iron and molten slag are discharged regularly;

[0013] (6) To efficiently melt scrap steel and solid waste blocks, the coke oven gas CO is controlled to be not less than 70.0%, the H2 is not less than 15.0%, and the CO2 content is between 2.0 and 4.0% by mass while meeting the smelting calorific value;

[0014] (7) To ensure that the generated molten iron can be used in subsequent processes, the molten iron is required to have a TFe content of 97.5-98% by mass, a C content of not less than 2%, a Si content of not more than 0.1%, a P content of not more than 0.02%, and a S content of not more than 0.04%.

[0015] Furthermore, the blocks are cubes, cylinders and / or hexagons.

[0016] Furthermore, by mass percentage, 90% of scrap steel and 10% of solid waste are put into a melting furnace in layers and batches together with coke and flux for melting.

[0017] Furthermore, by mass percentage, 80% of scrap steel and 20% of solid waste are put into a melting furnace in layers and batches together with coke and flux for melting.

[0018] Furthermore, by mass percentage, 70% of scrap steel and 30% of solid waste are put into a melting furnace in layers and batches together with coke and flux for melting.

[0019] Furthermore, the coke oven gas and hot air are mixed and pressurized and then sprayed into the smelting furnace through a spray gun from the bottom of the furnace. The smelting temperature in the furnace is 1550°C, the smelting time is controlled at 40 minutes, and the final products of the smelting are molten iron and smelting slag.

[0020] Compared with the prior art, the beneficial technical effects of the present invention are:

[0021] Compared with the blast furnace process, the technical advantage of the present invention is that no iron ore is used and the amount of coke used is very small and is only used as a carburizing agent. The coke oven gas provides heat and reduction, and the overall process has low clean carbon emissions, which is in line with the development route of low-carbon green steel smelting. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is described in detail below in conjunction with the embodiments.

[0023] Example 1

[0024] The chemical composition analysis of the scrap steel used in the embodiment of the present invention by mass percentage is shown in Table 1; the chemical composition analysis of the iron-containing solid waste by mass percentage is shown in Table 2; the chemical composition analysis of the external flux by mass percentage is shown in Table 3; the chemical composition analysis of the coke oven gas by mass percentage is shown in Table 4.

[0025] Table 1 Chemical composition of scrap steel used in the examples, %

[0026] MFe C Si Mn P S Cr W Rest Scrap Steel 99.144 0.138 0.176 0.373 0.021 0.031 0.031 0.026 0.060

[0027] Table 2 Chemical composition of iron-containing solid waste used in the examples, %

[0028]

[0029] Table 3 Chemical composition of flux, %

[0030] name CaO <![CDATA[SiO2]]> MgO <![CDATA[Al2O3]]> <![CDATA[CO2 <!-- 2 -->]]> magnesite 4.580 43.810 0.250 51.360 Silica 96.090 1.780

[0031] Table 4 Chemical composition of coke oven gas, %

[0032] CO <![CDATA[CO2]]> <![CDATA[H2]]> <![CDATA[H2O]]> <![CDATA[N2]]> <![CDATA[CH4]]> Coke oven gas 71.51 2.590 18.580 2.150 4.170 1.000

[0033] The implementation steps are as follows:

[0034] (1) Solid waste and irregular steel scrap are made into blocks (cubes, cylinders and hexagons) with an equivalent diameter of 0.2 to 0.4 m;

[0035] (2) Further, by mass percentage, 90% of scrap steel and 10% of solid waste are melted together with coke and flux in layers and batches in a melting furnace. After the coke oven gas and hot air are mixed and pressurized, they are sprayed into the melting furnace from the bottom of the furnace through a spray gun. The melting temperature in the furnace is 1550°C, and the melting time is controlled at 40 minutes. The final products of the melting are molten iron and molten slag. Taking the composition of 1 t of molten iron as an example, the amount of scrap steel, solid waste, coke, coke oven gas and flux used are shown in Table 5, and the composition of molten iron and molten slag are shown in Table 6 and Table 7 respectively, which can be used in subsequent processes. Compared with the traditional blast furnace process, the carbon emissions are significantly reduced.

[0036] (3) The flue gas generated during melting and separation meets the emission standards after being treated by the desulfurization device, the denitrification device and the gravity dust removal device.

[0037] Example 2

[0038] This embodiment still uses the scrap steel, solid waste, flux and coke oven gas used in embodiment 1 as raw materials. The specific implementation steps are as follows:

[0039] (1) Solid waste and irregular steel scrap are made into blocks (cubes, cylinders and hexagons) with an equivalent diameter of 0.2 to 0.4 m;

[0040] (2) Further, by mass percentage, 80% of scrap steel and 20% of solid waste are melted together with coke and flux in layers and batches in a melting furnace. After the coke oven gas and hot air are mixed and pressurized, they are sprayed into the melting furnace from the bottom of the furnace through a spray gun. The melting temperature in the furnace is 1550°C, and the melting time is controlled at 40 minutes. The final products of the melting are molten iron and molten slag. Taking the composition of 1 t of molten iron as an example, the amount of scrap steel, solid waste, coke, coke oven gas and flux used are shown in Table 5, and the composition of molten iron and molten slag are shown in Table 6 and Table 7 respectively, which can be used in subsequent processes. Compared with the traditional blast furnace process, the carbon emissions are significantly reduced.

[0041] (3) The flue gas generated during melting and separation meets the emission standards after being treated by the desulfurization device, the denitrification device and the gravity dust removal device.

[0042] Example 3

[0043] This embodiment still uses the scrap steel, solid waste, flux and coke oven gas used in embodiment 1 as raw materials. The specific implementation steps are as follows:

[0044] (1) Solid waste and irregular steel scrap are made into blocks (cubes, cylinders and hexagons) with an equivalent diameter of 0.2 to 0.4 m;

[0045] (2) Further, by mass percentage, 70% of scrap steel and 30% of solid waste are melted together with coke and flux in layers and batches in a melting furnace. After the coke oven gas and hot air are mixed and pressurized, they are sprayed into the melting furnace from the bottom of the furnace through a spray gun. The melting temperature in the furnace is 1550°C, and the melting time is controlled at 40 minutes. The final products of the melting are molten iron and molten slag. Taking the composition of 1 t of molten iron as an example, the amount of scrap steel, solid waste, coke, coke oven gas and flux used are shown in Table 5, and the composition of molten iron and molten slag are shown in Table 6 and Table 7 respectively, which can be used in subsequent processes. Compared with the traditional blast furnace process, the carbon emissions are significantly reduced.

[0046] (3) The flue gas generated during melting and separation meets the emission standards after being treated by the desulfurization device, the denitrification device and the gravity dust removal device.

[0047] Table 5 Raw material and fuel consumption for melting, kg / t iron

[0048]

[0049] Table 6 Chemical composition of molten iron, %

[0050] Fe C Si Mn P S 97.795 2.000 0.100 0.005 0.020 0.035

[0051] Table 7 Mass of compounds in slag, kg / t iron

[0052]

[0053]

[0054] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A non-blast furnace ironmaking process for melting and separating scrap steel and solid waste using coke oven gas as the main heat source, characterized in that: Specifically include: (1) Making irregular scrap steel and solid waste into blocks with an equivalent diameter of 0.2 to 0.45 m; (2) using a material elevator to place scrap steel, solid waste blocks, coke and flux in batches and in layers into a melting furnace, adding scrap steel, solid waste blocks, flux and coke in layers according to type and proportion to melt the molten iron; (3) To ensure that the quality of the molten iron is up to standard, the carbon content of the coke is controlled to be not less than 86.0% and the sulfur content is not more than 0.70% by mass; (4) In order to ensure the quality of the generated molten iron, magnesite and silica are used as flux; in terms of mass percentage, the CaO content of magnesite is controlled to be no higher than 5.0%, the SiO2 content is no lower than 40.0%, the MgO content is between 0.15 and 0.35, and the SiO2 content of silica is controlled to be no lower than 95.0%; (5) The coke oven gas and hot air are mixed and sprayed into the furnace through a mixing nozzle to burn and continuously melt the scrap steel and solid waste to generate molten iron at 1400±20℃, and the molten iron and molten slag are discharged regularly; (6) To efficiently melt scrap steel and solid waste blocks, the coke oven gas CO is controlled to be not less than 70.0%, the H2 is not less than 15.0%, and the CO2 content is between 2.0 and 4.0% by mass while meeting the smelting calorific value; (7) To ensure that the generated molten iron can be used in subsequent processes, the molten iron is required to have a TFe content of 97.5-98% by mass, a C content of not less than 2%, a Si content of not more than 0.1%, a P content of not more than 0.02%, and a S content of not more than 0.04%.

2. The non-blast furnace ironmaking process for melting and separating scrap steel and solid waste using coke oven gas as the main heat source according to claim 1, characterized in that: The blocks are cubes, cylinders and / or hexagonal bodies.

3. The non-blast furnace ironmaking process for melting and separating scrap steel and solid waste using coke oven gas as the main heat source according to claim 1, characterized in that: Calculated by mass percentage, 90% scrap steel and 10% solid waste are put into the melting furnace in layers and batches together with coke and flux for melting.

4. The non-blast furnace ironmaking process for melting and separating scrap steel and solid waste using coke oven gas as the main heat source according to claim 1, characterized in that: Calculated by mass percentage, 80% scrap steel and 20% solid waste are put into the melting furnace in layers and batches together with coke and flux for melting.

5. The non-blast furnace ironmaking process for melting and separating scrap steel and solid waste using coke oven gas as the main heat source according to claim 1, characterized in that: Calculated by mass percentage, 70% scrap steel and 30% solid waste are put into the melting furnace in layers and batches together with coke and flux for melting.

6. The non-blast furnace ironmaking process for melting and separating scrap steel and solid waste using coke oven gas as the main heat source according to claim 1, characterized in that: The coke oven gas and hot air are mixed and pressurized and then sprayed into the smelting furnace through a spray gun from the bottom of the furnace. The smelting temperature in the furnace is 1550℃, the smelting time is controlled at 40 minutes, and the final products of smelting are molten iron and smelting slag.

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