Fuming slag ironmaking method

Abstract

The invention belongs to the technical field of fuming slag recycling, and particularly relates to a fuming slag ironmaking method. The method comprises the following steps: introducing fuming slag into a converting combustion furnace, adding a slag former and a reducing agent, and reacting to obtain molten iron and tailings; the molar weight of CO in the reaction atmosphere of the slag layer is controlled to be 95%-100% of the sum of CO and CO2. According to the method, iron in the fuming furnace slag can be fully recycled under the condition of low energy consumption, molten iron which can be directly supplied to factories for use is obtained, meanwhile, the obtained tailings can be used as building raw materials, and the fuming furnace slag can be effectively utilized.

Description

Technical Field

[0001] The invention belongs to the technical field of recycling and utilizing fumed slag, and in particular relates to a method for smelting iron using fumed slag. Background Art

[0002] In the nonferrous metallurgical industry, various slags produced by fuming furnaces are mostly used, but a certain amount of valuable metals still exist in the fumed slag obtained after treatment in the fuming furnace. In the prior art, fumed slag is mostly stored and treated, or only sold as a raw material for building materials, and the valuable metals therein are not effectively utilized. There are also some methods in the prior art for reusing fumed slag in other forms, but these methods have low iron utilization rates or too high energy consumption, and cannot achieve the effective utilization of iron elements in the fumed slag. At the same time, among the common smelting furnaces, side-blowing smelting belongs to the enhanced molten pool smelting technology, which has the advantages of high smelting intensity, strong processing capacity, and excellent dynamic conditions. Summary of the invention

[0003] Therefore, the technical problem to be solved by the present invention is to overcome the defects of low iron utilization rate and high energy consumption when using fumed slag in the prior art, thereby providing a fumed slag ironmaking method.

[0004] To this end, the present invention provides the following technical solutions.

[0005] The invention provides a fumed slag ironmaking method, comprising the following steps: introducing the fumed slag into a blowing combustion furnace, adding a slag-forming agent and a reducing agent, reacting to obtain molten iron and tailings; and controlling the molar amount of CO in the reaction atmosphere of the slag layer to account for 95% to 100% of the sum of CO and CO2.

[0006] Optionally, a slag-forming agent is added to control the binary basicity CaO / SiO2 in the furnace to 0.3~1.5; optionally, the binary basicity CaO / SiO2 is 0.4~1.1.

[0007] Optionally, the mass of the reducing agent is 11% to 22% of the mass of the fumed slag.

[0008] Optionally, the reaction temperature is 1350~1550℃; Optionally, the reaction temperature is 1400~1500℃.

[0009] Optionally, the reaction also produces flue gas.

[0010] Optionally, the flue gas temperature exiting the blowing combustion furnace is 100-300°C higher than the slag temperature.

[0011] Optionally, the reaction is carried out in an oxygen-rich atmosphere; optionally, the volume percentage of oxygen in the oxygen-rich atmosphere is 40% to 99%.

[0012] Optionally, the reducing agent includes at least one of coal, anthracite, coke, and petroleum coke.

[0013] Optionally, the slag-forming agent includes at least one of limestone, dolomite and quicklime.

[0014] Optionally, the particle size of the slag-forming agent is less than 100 mm.

[0015] Optionally, the particle size of the reducing agent is less than 100 mm.

[0016] Optionally, the fumed slag is liquid fumed slag and / or cold fumed slag directly transferred from a fuming furnace.

[0017] Optionally, the blowing combustion furnace includes at least one of a side-blowing combustion furnace, a top-blowing combustion furnace, and a bottom-blowing combustion furnace.

[0018] The beneficial effects of the present invention are: The method for recovering fumed slag provided by the present invention comprises the following steps: passing the fumed slag into a blowing combustion furnace, adding a slag-forming agent and a reducing agent, reacting, and obtaining molten iron and tailings; and controlling the molar amount of CO in the reaction atmosphere of the slag layer to account for 95% to 100% of the sum of CO and CO2. This method can fully recover the iron in the fumed slag under low energy consumption, and obtain molten iron that can be directly supplied to the factory, and the tailings obtained at the same time can be used as a raw material for building materials, and the fumed slag can be effectively utilized. The fumed slag is treated by using a blowing combustion furnace, and the reducing agent is burned and participates in the reduction reaction at the same time, and the heat generated is sufficient to support the guarantee of the reaction temperature, without the need to add additional fuel. DETAILED DESCRIPTION

[0019] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0020] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0021] The detection methods for each element in the product are all chemical analysis detection methods. The determination method of iron content in tailings refers to GB / T 6730.6-2016, and the determination method of iron content in molten iron refers to GB / T 223.70-2008. The recovery rate of iron is calculated using the formula "(weight of element in raw material - weight of element in tailings) / weight of element in raw material".

[0022] Experimental drugs The composition of the liquid fumed slag used is shown in Table 1.

[0023] Table 1

[0024] Example 1 This embodiment provides a method for recovering fumed slag. First, a slag-making agent and a reducing agent are ground to a particle size of less than 100 mm. The specific recovery steps are as follows: As shown in Table 1, the liquid fumed slag flows intermittently into the side-blown combustion furnace through the chute, and anthracite as a reducing agent of 14% of the mass of the fumed slag is added to the side-blown combustion furnace, and limestone as a slag-making agent is added. The binary basicity CaO / SiO2 in the furnace is controlled to be 0.5, and the atmosphere is controlled to be an oxygen-rich atmosphere with an oxygen volume percentage of about 80%. The reaction is carried out at 1500°C to obtain molten iron and tailings, and the molten iron is continuously discharged from the iron mouth through the siphon port. During the reaction, the molar amount of CO in the reaction atmosphere of the slag layer is controlled to account for 96% of the sum of CO and CO2. The flue gas obtained by combustion is used to supplement the heat of the side-blown combustion furnace, so that the final flue gas temperature is 100°C higher than the slag temperature. The obtained molten iron can be directly used for steelmaking, and the tailings can be used in the construction industry.

[0025] The method can process 200,000 tons of liquid fumed slag annually.

[0026] Iron content in tailings: 1.5%.

[0027] Iron content in molten iron: 96.9%; Iron recovery rate: 96.64%.

[0028] Example 2 This embodiment provides a method for recovering fumed slag. First, a slag-making agent and a reducing agent are ground to a particle size of less than 100 mm. The specific recovery steps are as follows: As shown in Table 1, the liquid fumed slag flows intermittently into the side-blown combustion furnace through the chute, and 20% of the mass of the fumed slag is added to the side-blown combustion furnace. The reducing agent coke and slag-making agent quicklime are added, and the binary basicity CaO / SiO2 in the furnace is controlled to be 1.1. The atmosphere is controlled to be an oxygen-rich atmosphere with an oxygen volume percentage of about 60%. The reaction is carried out at 1550°C to obtain molten iron and tailings, and the molten iron is continuously discharged from the iron mouth through the siphon port. During the reaction, the molar amount of CO in the reaction atmosphere of the slag layer is controlled to account for 98% of the sum of CO and CO2. The flue gas obtained by combustion is used to supplement the heat of the side-blown combustion furnace, so that the final flue gas temperature is 200°C higher than the slag temperature. The obtained molten iron can be directly used for steelmaking, and the tailings can be used in the construction industry.

[0029] The method can process 200,000 tons of liquid fumed slag annually.

[0030] Iron content in tailings: 0.5%.

[0031] Iron content in molten iron: 94.9%; Iron recovery rate: 98.22%.

[0032] Example 3 This embodiment provides a method for recovering fumed slag. First, a slag-making agent and a reducing agent are ground to a particle size of less than 100 mm. The specific recovery steps are as follows: As shown in Table 1, the liquid fumed slag flows intermittently into the side-blown combustion furnace through the chute, and the reducing agent coal of 22% of the mass of the fumed slag is added into the side-blown combustion furnace, and the slag-making agent limestone is added. The binary basicity CaO / SiO2 in the furnace is controlled to be 0.8, and the atmosphere is controlled to be an oxygen-rich atmosphere with an oxygen volume percentage of 40% to 50%. The reaction is carried out at 1400°C to obtain molten iron and tailings, and the molten iron is continuously discharged from the iron mouth through the siphon port. During the reaction, the molar amount of CO in the reaction atmosphere of the slag layer is controlled to account for 99% of the sum of CO and CO2. The flue gas obtained by combustion is used to supplement the heat of the side-blown combustion furnace, so that the final flue gas temperature is 300°C higher than the slag temperature. The obtained molten iron can be directly used for steelmaking, and the tailings can be used in the construction industry.

[0033] The method can process 200,000 tons of liquid fumed slag annually.

[0034] Iron content in tailings: 2.5%.

[0035] Iron content in molten iron: 95.9%; Iron recovery rate: 95.02%.

[0036] Comparative Example 1 This comparative example provides a method for recovering fumed slag, which differs from Example 1 only in that, during the reaction, the atmosphere is controlled to be an oxygen-rich atmosphere with an oxygen volume percentage of about 95%, and the molar amount of CO in the reaction atmosphere of the slag layer is controlled to account for 85% of the sum of CO and CO2.

[0037] The iron content in the obtained tailings is 10%.

[0038] The iron content in the obtained molten iron is 98.7%; the iron recovery rate is 80.98%.

[0039] By using the fumed slag recovery method in the present application, 200,000 tons of liquid fumed slag can be processed annually. The processing speed is efficient, and the iron recovery rate can reach more than 95%, realizing the effective recovery of iron in the fumed slag. The iron content in the molten iron is more than 94%, and the molten iron can be directly used in the production and manufacture of steel or other ferroalloys. At the same time, the smelting is directly carried out in the blowing furnace, and the reducing agent is burned and participates in the reduction reaction at the same time, saving part of the energy consumption of heating. However, the molar amount of CO in the reaction atmosphere of the slag layer controlled in the comparative example is not within the range specified in the present application. Although the iron content in the obtained molten iron is very high, the iron content in the tailings is also very high, and the final iron recovery rate is low, and the full recovery of iron in the fumed slag cannot be achieved.

[0040] Obviously, the above embodiments are merely examples for clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the protection scope of the invention.

Claims

1. A fumed slag ironmaking method, characterized in that: The method comprises the following steps: introducing the fumed slag into a blowing combustion furnace, adding a slag-making agent and a reducing agent, reacting to obtain molten iron and tailings; The molar amount of CO in the reaction atmosphere of the slag layer is controlled to account for 95%~100% of the sum of CO and CO2.

2. The fumed slag ironmaking method according to claim 1, characterized in that: Add slag-forming agent to control the binary basicity CaO / SiO2 in the furnace to 0.3-1.5; optionally, the binary basicity CaO / SiO2 is 0.4-1.1; And / or, the mass of the reducing agent is 11% to 22% of the mass of the fumed slag.

3. The fumed slag ironmaking method according to claim 1 or 2, characterized in that: The reaction temperature is 1350~1550℃; optionally, the reaction temperature is 1400~1500℃.

4. The fumed slag ironmaking method according to any one of claims 1 to 3, characterized in that: The reaction also produces flue gas.

5. The fumed slag ironmaking method according to claim 4, characterized in that: The flue gas temperature leaving the blowing combustion furnace is 100~300℃ higher than the slag temperature.

6. The fumed slag ironmaking method according to any one of claims 1 to 5, characterized in that: The reaction is carried out in an oxygen-rich atmosphere; optionally, the volume percentage of oxygen in the oxygen-rich atmosphere is 40% to 99%.

7. The fumed slag ironmaking method according to any one of claims 1 to 6, characterized in that: The reducing agent includes at least one of coal, anthracite, coke, and petroleum coke; And / or, the slag-forming agent includes at least one of limestone, dolomite and quicklime.

8. The fumed slag ironmaking method according to claim 7, characterized in that: The particle size of the slag-forming agent is less than 100 mm; And / or, the particle size of the reducing agent is less than 100 mm.

9. The fumed slag ironmaking method according to any one of claims 1 to 8, characterized in that: The fumed slag is liquid fumed slag and / or cold fumed slag directly transferred from a fuming furnace.

10. The fumed slag ironmaking method according to any one of claims 1 to 9, characterized in that: The blowing combustion furnace includes at least one of a side-blowing combustion furnace, a top-blowing combustion furnace, and a bottom-blowing combustion furnace.

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