KR desulfurization slag resource utilization process

Abstract

The invention relates to the field of metallurgical solid waste resource utilization, in particular to a KR desulfurization slag resource utilization process which comprises the following steps: (1) slagging off molten iron to obtain pre-desulfurization slag and slagging-off molten iron, carrying out granulation cooling and magnetic roller iron removal on the pre-desulfurization slag to obtain iron particles and pre-desulfurization slag tailings, and returning the iron particles to a blast furnace for utilization, the slag tailings before desulfurization are prepared into superfine slag powder; and (2) carrying out KR desulfurization on the drossing molten iron obtained in the step (1), then carrying out drossing to obtain desulfurized slag, carrying out primary crushing and secondary crushing on the desulfurized slag to obtain secondarily crushed desulfurized slag, and returning the secondarily crushed desulfurized slag to a sintering process for reuse. According to the method, 100% resource utilization of the KR desulfurization slag can be achieved, iron, calcium and other resources are effectively recycled, carbon dioxide emission is reduced, the hidden danger of environmental protection is eliminated, and good economic benefits and social benefits are achieved.

Description

Technical Field

[0001] The invention relates to the field of resource utilization of metallurgical solid waste, and in particular to a process for resource utilization of KR desulfurization slag. Background Art

[0002] The main hot metal desulfurization process of domestic steel enterprises is the KR hot metal desulfurization process, and the desulfurizer used is mainly quicklime (CaO). KR desulfurization slag is a by-product of the KR hot metal desulfurization process, with a production volume of about 7-10kg / t hot metal. It contains a large amount of valuable elements such as iron and calcium, and a small amount of harmful elements such as sulfur. At present, the treatment process of domestic KR desulfurization slag is mainly the "drip irrigation method". That is, the high-temperature KR desulfurization slag in the slag tank is slowly dripped for about 24 hours to fully pulverize and cool the KR desulfurization slag. The KR desulfurization slag treated by the "drip irrigation method" is then processed by magnetic separation to recover the iron in the KR desulfurization slag, and the remaining tailings are mainly stored. There are two main shortcomings in this treatment process: First, because the desulfurization slag contains iron and sulfur, SO2 and H2S will be generated during the "drip irrigation method" cooling process, which affects the environment; second, the large amount of tailings storage not only occupies land resources but also poses environmental risks.

[0003] The proposal with application number 202110514292.0, "A method for internal recycling of KR desulfurized slag iron plant", mainly includes: crushing KR desulfurized slag and performing magnetic separation to obtain slag iron and tailings; then subjecting the tailings to high-temperature oxidation desulfurization treatment, specifically heating the tailings to 1200-1350℃ and keeping warm for 10-40min to obtain sulfur-containing flue gas and pre-melted slag; then collecting and treating the sulfur-containing flue gas, and using the pre-melted slag as slag-making material for the early stage of converter slag-making, so as to realize the recycling of KR desulfurized slag within the steel plant. This process requires high-temperature desulfurization of the tailings before use, which consumes a lot of energy.

[0004] The scheme with application number 202010107303.9, "A method for efficient resource utilization of KR desulfurization slag", mainly includes: first, crushing the desulfurization slag to a specified particle size, and then obtaining slag and tailings through magnetic separation. The slag is returned to the steelmaking process to replace scrap steel for reuse; the tailings are further ground to replace quicklime for sintering dry or semi-dry desulfurization process, and finally all the desulfurization slag is utilized. The tailings of this process need to be further ground to replace quicklime for sintering dry or semi-dry desulfurization process. Because the grindability of steel slag is poor, the energy consumption of further grinding is high. At the same time, because the calcium oxide content of the desulfurization slag is lower than that of the quicklime used for desulfurization, its desulfurization effect on sintering flue gas needs to be further verified.

[0005] The scheme with application number 202010107302.4, "A method for comprehensive treatment of KR desulfurization slag", mainly includes: firstly, crushing the desulfurization slag to a specified particle size, and then obtaining slag iron and tailings through magnetic separation, and returning the slag iron to the steelmaking process to replace scrap steel for reuse; the tailings participate in sintering ore blending, and replace sintering iron-containing raw materials and flux according to a certain ratio. This process returns the slag iron obtained by magnetic separation to the steelmaking process instead of scrap steel. Because the desulfurization slag iron contains a high sulfur content, it is easy to increase the sulfur content in molten steel and affect the quality of molten steel. Summary of the invention

[0006] The purpose of the present invention is to overcome the problems of high energy consumption and impact on product quality in the existing KR desulfurization slag treatment technology, and to provide a KR desulfurization slag resource utilization process. The method can achieve 100% resource utilization of KR desulfurization slag, effectively recover resources such as iron and calcium, reduce carbon dioxide emissions, eliminate environmental risks, and has good economic and social benefits.

[0007] In order to achieve the above object, the present invention provides a KR desulfurization slag resource utilization process, which comprises the following steps:

[0008] (1) slagging the molten iron to obtain pre-desulfurization slag and molten iron after slagging, granulating and cooling the pre-desulfurization slag and removing iron with a magnetic drum to obtain iron particles and pre-desulfurization slag tailings, returning the iron particles to the blast furnace for utilization, and preparing the pre-desulfurization slag tailings into slag powder; wherein the magnetic field intensity on the surface of the magnetic drum is 1800-2400GS, and the rotation speed is 10-50r / mim;

[0009] (2) performing KR desulfurization on the molten iron after slagging obtained in step (1), and then performing slagging to obtain desulfurized slag, performing primary crushing and secondary crushing on the desulfurized slag to obtain secondary crushed desulfurized slag, and returning the secondary crushed desulfurized slag to the sintering process for reuse; wherein, in the secondary crushed desulfurized slag, the material with a particle size greater than 5 mm does not exceed 1% of the total weight of the secondary crushed desulfurized slag, and the material with a particle size less than 0.075 mm does not exceed 10% of the total weight of the secondary crushed desulfurized slag.

[0010] In step (1) of the present invention, in order to improve the desulfurization efficiency, the molten iron needs to be deslagging before desulfurization, wherein the specific operation of deslagging the molten iron is: using a deslagging machine to scrape off the slag on the surface of the molten iron.

[0011] In step (1) of the present invention, the INBA method is used for granulation and cooling; this method has a high treatment efficiency for the pre-desulfurization slag, and the pre-desulfurization slag after treatment has stable performance, which is conducive to preparing slag micropowder and ensuring its performance.

[0012] In the present invention, magnetic drum is used for iron removal, and the process conditions are controlled within the above range, the content of TFe in the obtained iron particles is ≥85wt%, the particle size of the iron particles is <120mm; the content of MFe in the slag tailings before desulfurization is <1wt%.

[0013] Furthermore, the pre-desulfurization slag obtained in step (1) is dried and then ground to a specific surface area greater than 400m 2 / kg, slag powder can be obtained.

[0014] In step (2) of the present invention, the KR desulfurization is a conventional operation in the art, and the specific steps are: adding a desulfurizer to the molten iron after slagging obtained in step (1), and then performing KR mechanical stirring; wherein the desulfurizer used is a desulfurizer conventionally used in the art, and KR mechanical stirring is also a conventional operation process in the art.

[0015] In step (2), after the KR desulfurization is completed, the specific operation of slag removal is also: using a slag remover to remove the slag on the surface of the molten iron.

[0016] In a preferred case, the reason for performing primary and secondary crushing on the desulfurization slag in step (2) is that the primary crushing is for the molten desulfurization slag, and its purpose is to prevent the molten desulfurization slag from sticking together to form large lumps, which is not conducive to subsequent processing. During the primary crushing process, the desulfurization slag can also be cooled; the secondary crushing is for the cold desulfurization slag, and its purpose is to meet the requirements of subsequent sintering utilization after processing.

[0017] Further in step (2), the desulfurization slag is subjected to primary crushing to obtain primary crushed desulfurization slag, and then the primary crushed desulfurization slag is subjected to secondary crushing to obtain secondary crushed desulfurization slag.

[0018] Furthermore, in step (2), in the desulfurization slag after the primary crushing, the material with a particle size greater than 200 mm does not exceed 10% of the total weight of the desulfurization slag after the primary crushing, so that it can be used as raw material to enter the secondary crushing system for processing.

[0019] Wherein, in step (2), the temperature of the desulfurized slag after the primary crushing is ≤65°C.

[0020] In the preferred case of step (2), different crushing methods are used in the primary crushing and the secondary crushing according to the material characteristics. Specifically, the primary crushing method is roller crushing; and the secondary crushing method is hammer crushing or rod milling.

[0021] In step (2) of the present invention, the particle size of the desulfurized slag after secondary crushing is controlled within a corresponding range in order to meet the requirements for sintering utilization.

[0022] The method is to return the obtained secondary crushed desulfurized slag to the sintering process for reuse, and the sulfur dioxide concentration at the outlet of the sintering flue gas desulfurization system is not higher than 35mg / m 3 , meeting ultra-low emission requirements.

[0023] The molten iron after slagging in step (2) of the present invention is used in a converter or electric furnace steelmaking process.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] 1) This technology combines the characteristics of the KR desulfurization process and classifies and processes the slag produced before and after KR desulfurization according to their different characteristics, thus achieving 100% resource utilization of KR desulfurization slag.

[0026] 2) This technology combines the steelmaking process to achieve the recycling of resources such as iron and calcium in KR desulfurization slag, and effectively controls the impact of sulfur in the desulfurization slag on the system.

[0027] 3) Compared with the existing technology, this technology avoids the high-temperature desulfurization and fine grinding of desulfurization slag and tailings, saving energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0029] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0030] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0031] The KR desulfurization slag resource utilization process of the present invention is as follows Figure 1 As shown, the present invention will be described in detail below through examples.

[0032] Example 1

[0033] (1) Before desulfurization of molten iron, a slag scraper is used to scrape off the slag on the surface of the molten iron to obtain pre-desulfurization slag and molten iron after slag scraping. The pre-desulfurization slag is granulated and cooled by the INBA method, and then the iron is removed by a magnetic drum to obtain iron particles (TFe content is 88.37wt%, particle size <120mm) and pre-desulfurization slag tail (MFe content is 0.88wt%), and the iron particles are returned to the blast furnace for utilization; wherein the magnetic field intensity on the surface of the magnetic drum is 1800GS, and the rotation speed is 16r / min;

[0034] (2) adding a desulfurizing agent to the molten iron after slagging obtained in step (1), and then performing KR mechanical stirring. After the stirring, a slagging machine is used to scrape off the slag on the surface of the molten iron to obtain desulfurized slag. The desulfurized slag is subjected to primary crushing (the primary crushing method is roller crushing) to a particle size of less than 200 mm to obtain primary crushed desulfurized slag. The primary crushed desulfurized slag is then subjected to secondary crushing (the secondary crushing method is rod grinding) to a particle size of less than 5 mm to obtain secondary crushed desulfurized slag (the total weight of the secondary crushed desulfurized slag is 100wt%). The main chemical components of the desulfurization slag after secondary crushing include: TFe content is 26.00wt%, MFe content is 24.78wt%, CaO content is 44.35wt%, MgO content is 1.38wt%, Al2O3 content is 2.40wt%, SiO2 content is 14.70wt%, S content is 1.51wt%, P content is 0.07wt%), and the desulfurization slag after secondary crushing is returned to the sintering process for reuse; wherein, the temperature of the desulfurization slag after primary crushing is ≤65°C.

[0035] Example 2

[0036] (1) Before desulfurization of molten iron, a slag scraper is used to scrape off the slag on the surface of the molten iron to obtain pre-desulfurization slag and molten iron after slag scraping. The pre-desulfurization slag is granulated and cooled by the INBA method, and then the iron is removed by a magnetic drum to obtain iron particles (TFe content is 87.58wt%, particle size <120mm) and pre-desulfurization slag tail (MFe content is 0.74wt%), and the iron particles are returned to the blast furnace for utilization; wherein the magnetic field intensity on the surface of the magnetic drum is 1900GS, and the rotation speed is 13r / min;

[0037] (2) adding a desulfurizing agent to the molten iron after slagging obtained in step (1), and then performing KR mechanical stirring. After the stirring, a slagging machine is used to scrape off the slag on the surface of the molten iron to obtain desulfurized slag. The desulfurized slag is subjected to primary crushing (the primary crushing method is roller crushing) to a particle size of less than 200 mm to obtain primary crushed desulfurized slag. The primary crushed desulfurized slag is then subjected to secondary crushing (the secondary crushing method is rod grinding) to a particle size of less than 5 mm to obtain secondary crushed desulfurized slag (the total weight of the secondary crushed desulfurized slag is 100wt%). The main chemical components of the desulfurization slag after secondary crushing include: TFe content is 31.37wt%, MFe content is 26.17wt%, CaO content is 49.07wt%, MgO content is 1.33wt%, Al2O3 content is 2.39wt%, SiO2 content is 13.95wt%, S content is 1.60wt%, P content is 0.04wt%), and the desulfurization slag after secondary crushing is returned to the sintering process for reuse; wherein, the temperature of the desulfurization slag after primary crushing is ≤65°C.

[0038] Example 3

[0039] (1) Before desulfurization of molten iron, a slag scraper is used to scrape off the slag on the surface of the molten iron to obtain pre-desulfurization slag and molten iron after slag scraping. The pre-desulfurization slag is granulated and cooled by the INBA method, and then the iron is removed by a magnetic drum to obtain iron particles (TFe content is 86.58wt%, particle size <120mm) and pre-desulfurization slag tail (MFe content is 0.90wt%), and the iron particles are returned to the blast furnace for utilization; wherein the magnetic field intensity on the surface of the magnetic drum is 2000GS, and the rotation speed is 10r / min;

[0040] (2) adding a desulfurizing agent to the molten iron after slagging obtained in step (1), and then performing KR mechanical stirring. After the stirring, a slagging machine is used to scrape off the slag on the surface of the molten iron to obtain desulfurized slag. The desulfurized slag is subjected to primary crushing (the primary crushing method is roller crushing) to a particle size of less than 200 mm to obtain primary crushed desulfurized slag. The primary crushed desulfurized slag is then subjected to secondary crushing (the secondary crushing method is rod grinding) to a particle size of less than 5 mm to obtain secondary crushed desulfurized slag (the total weight of the secondary crushed desulfurized slag is 100wt%). The main chemical components of the desulfurization slag after secondary crushing include: TFe content is 33.27wt%, MFe content is 26.18wt%, CaO content is 42.07wt%, MgO content is 1.41wt%, Al2O3 content is 2.34wt%, SiO2 content is 13.89wt%, S content is 1.46wt%, P content is 0.04wt%), and the desulfurization slag after secondary crushing is returned to the sintering process for reuse; wherein, the temperature of the desulfurization slag after primary crushing is ≤65°C.

[0041] Example 4

[0042] (1) Before desulfurization of molten iron, a slag scraper is used to scrape off the slag on the surface of the molten iron to obtain pre-desulfurization slag and molten iron after slag scraping. The pre-desulfurization slag is granulated and cooled by the INBA method, and then the iron is removed by a magnetic drum to obtain iron particles (TFe content is 86.27wt%, particle size <120mm) and pre-desulfurization slag tail (MFe content is 0.72wt%), and the iron particles are returned to the blast furnace for utilization; wherein the magnetic field intensity on the surface of the magnetic drum is 2000GS, and the rotation speed is 20r / min;

[0043] (2) adding a desulfurizing agent to the molten iron after slagging obtained in step (1), and then performing KR mechanical stirring, after which the slag on the surface of the molten iron is removed by a slagging machine to obtain desulfurized slag, performing primary crushing (the primary crushing method is roller crushing) on ​​the desulfurized slag to a particle size of less than 200 mm, and obtaining primary crushed desulfurized slag, and then performing secondary crushing (the secondary crushing method is rod grinding) on ​​the primary crushed desulfurized slag to a particle size of less than 5 mm, and obtaining secondary crushed desulfurized slag (the total weight of the secondary crushed desulfurized slag is 100wt%). The main chemical components of the desulfurization slag after secondary crushing include: TFe content is 40.20wt%, MFe content is 34.29wt%, CaO content is 28.60wt%, MgO content is 0.37wt%, Al2O3 content is 1.32wt%, SiO2 content is 5.77wt%, S content is 0.47wt%, P content is 0.03wt%), and the desulfurization slag after secondary crushing is returned to the sintering process for reuse; wherein, the temperature of the desulfurization slag after primary crushing is ≤65℃.

[0044] Example 5

[0045] (1) Before desulfurization of molten iron, a slag scraper is used to scrape off the slag on the surface of the molten iron to obtain pre-desulfurization slag and molten iron after slag scraping. The pre-desulfurization slag is granulated and cooled by the INBA method, and then the iron is removed by a magnetic drum to obtain iron particles (TFe content is 85.69wt%, particle size <120mm) and pre-desulfurization slag tail (MFe content is 0.58wt%), and the iron particles are returned to the blast furnace for utilization; wherein the magnetic field intensity on the surface of the magnetic drum is 2300GS, and the rotation speed is 15r / min;

[0046] (2) adding a desulfurizing agent to the molten iron after slagging obtained in step (1), and then performing KR mechanical stirring, after which the slag on the surface of the molten iron is removed by a slagging machine to obtain desulfurized slag, performing primary crushing (the primary crushing method is roller crushing) on ​​the desulfurized slag to a particle size of less than 200 mm, and obtaining primary crushed desulfurized slag, and then performing secondary crushing (the secondary crushing method is rod grinding) on ​​the primary crushed desulfurized slag to a particle size of less than 5 mm, and obtaining secondary crushed desulfurized slag (the total weight of the secondary crushed desulfurized slag is 100wt%). The main chemical components of the desulfurization slag after secondary crushing include: TFe content is 35.78wt%, MFe content is 28.04wt%, CaO content is 32.59wt%, MgO content is 0.79wt%, Al2O3 content is 1.62wt%, SiO2 content is 8.33wt%, S content is 0.92wt%, P content is 0.04wt%), and the desulfurization slag after secondary crushing is returned to the sintering process for reuse; wherein, the temperature of the desulfurization slag after primary crushing is ≤65℃.

[0047] Example 6

[0048] (1) Before desulfurization of molten iron, a slag scraper is used to scrape off the slag on the surface of the molten iron to obtain pre-desulfurization slag and molten iron after slag scraping. The pre-desulfurization slag is granulated and cooled by the INBA method, and then the iron is removed by a magnetic drum to obtain iron particles (TFe content is 87.03wt%, particle size <120mm) and pre-desulfurization slag tail (MFe content is 0.66wt%), and the iron particles are returned to the blast furnace for utilization; wherein the magnetic field intensity on the surface of the magnetic drum is 2300GS, and the rotation speed is 10r / min;

[0049] (2) adding a desulfurizing agent to the molten iron after slagging obtained in step (1), and then performing KR mechanical stirring, after which the slag on the surface of the molten iron is removed by a slagging machine to obtain desulfurized slag, performing primary crushing (the primary crushing method is roller crushing) on ​​the desulfurized slag to a particle size of less than 200 mm, and obtaining primary crushed desulfurized slag, and then performing secondary crushing (the secondary crushing method is rod grinding) on ​​the primary crushed desulfurized slag to a particle size of less than 5 mm, and obtaining secondary crushed desulfurized slag (the total weight of the secondary crushed desulfurized slag is 100wt%). The main chemical components of the desulfurization slag after secondary crushing include: TFe content is 28.61wt%, MFe content is 22.31wt%, CaO content is 40.64wt%, MgO content is 1.96wt%, Al2O3 content is 2.60wt%, SiO2 content is 9.81wt%, S content is 1.35wt%, P content is 0.05wt%), and the desulfurization slag after secondary crushing is returned to the sintering process for reuse; wherein, the temperature of the desulfurization slag after primary crushing is ≤65℃.

[0050] Comparative Example 1

[0051] (1) Before desulfurization of molten iron, a slag scraper is used to scrape off the slag on the surface of the molten iron to obtain pre-desulfurization slag and molten iron after slag scraping. The pre-desulfurization slag is granulated and cooled by the INBA method, and then the iron is removed by a magnetic drum to obtain iron particles (TFe content is 76.54wt%, particle size <120mm) and pre-desulfurization slag tail (MFe content is 2.33wt%), and the iron particles are returned to the blast furnace for utilization; wherein the magnetic field strength on the surface of the magnetic drum is 3000GS, and the rotation speed is 60r / min;

[0052] (2) adding a desulfurizing agent to the molten iron after slagging obtained in step (1), and then performing KR mechanical stirring, after which the slag on the surface of the molten iron is removed by a slagging machine to obtain desulfurized slag, performing primary crushing (the primary crushing method is roller crushing) on ​​the desulfurized slag to a particle size of less than 200 mm, and obtaining primary crushed desulfurized slag, and then performing secondary crushing (the secondary crushing method is rod grinding) on ​​the primary crushed desulfurized slag to a particle size of less than 10 mm, and obtaining secondary crushed desulfurized slag (the secondary crushed desulfurized slag is the secondary crushed desulfurized slag). Based on the total weight of 100wt%, the main chemical components of the desulfurization slag after secondary crushing are: TFe content is 27.12wt%, MFe content is 20.78wt%, CaO content is 40.26wt%, MgO content is 1.19wt%, Al2O3 content is 2.37wt%, SiO2 content is 9.88wt%, S content is 0.93wt%, and P content is 0.03wt%); wherein, the temperature of the desulfurization slag after primary crushing is ≤65℃.

[0053] Comparative Example 2

[0054] (1) Before desulfurization of molten iron, a slag scraper is used to scrape off the slag on the surface of the molten iron to obtain pre-desulfurization slag and molten iron after slag scraping. The pre-desulfurization slag is granulated and cooled by the INBA method, and then the iron is removed by a magnetic drum to obtain iron particles (TFe content is 80.26wt%, particle size <120mm) and pre-desulfurization slag tail (MFe content is 2.51wt%), and the iron particles are returned to the blast furnace for utilization; wherein the magnetic field strength on the surface of the magnetic drum is 1500GS, and the rotation speed is 60r / min;

[0055] (2) adding a desulfurizing agent to the molten iron after slagging obtained in step (1), and then performing KR mechanical stirring, after which the slag on the surface of the molten iron is removed by a slagging machine to obtain desulfurized slag, performing primary crushing (the primary crushing method is roller crushing) on ​​the desulfurized slag to a particle size of less than 200 mm, and obtaining primary crushed desulfurized slag, and then performing secondary crushing (the secondary crushing method is rod grinding) on ​​the primary crushed desulfurized slag to a particle size of less than 2 mm, and obtaining secondary crushed desulfurized slag (the total weight of the secondary crushed desulfurized slag is 100 wt % The main chemical components of the desulfurization slag after secondary crushing include: TFe content is 30.14wt%, MFe content is 23.53wt%, CaO content is 39.36wt%, MgO content is 2.07wt%, Al2O3 content is 2.56wt%, SiO2 content is 10.88wt%, S content is 1.07wt%, P content is 0.04wt%), and the desulfurization slag after secondary crushing is returned to the sintering process for reuse; wherein, the temperature of the desulfurization slag after primary crushing is ≤65°C.

[0056] Test Example 1

[0057] The pre-desulfurization slag and tailings obtained in step (1) of Example 1-6 and Comparative Example 1-2 are dried and then ground to a specific surface area greater than 400 m 2 / kg, slag powder was obtained, and the activity index of the slag powder was measured according to GB / T 18046-2008 "Granulated blast furnace slag powder for cement and concrete". The measurement results are shown in Table 1.

[0058] Table 1

[0059]

[0060] As can be seen from Table 1, the 7d and 28d activity indexes of the slag powders prepared in Examples 1 to 6 all meet the S95 technical index requirements of GB / T 18046-2008 "Granulated blast furnace slag powder for cement and concrete". Comparative Examples 1 to 2 Since the process of removing iron by magnetic drum does not meet the requirements, the content of MFe in the obtained slag tailings before desulfurization exceeds 1wt%, affecting the performance index of the slag powder, so the 7d and 28d activity indexes of the prepared slag powders cannot meet the S95 technical index requirements of GB / T 18046-2008 "Granulated blast furnace slag powder for cement and concrete".

[0061] Test Example 2

[0062] Taking the maximum S content of 1.6wt% of the desulfurized slag after secondary crushing obtained in Examples 1 to 6 and Comparative Examples 1 to 2 as an example, that is, Example 2, combined with 300m 2The relevant process parameters of the sintering machine are used to calculate the impact of returning the desulfurized slag to the sintering system on the sulfur dioxide emissions. The specific process and calculation are shown in Table 2.

[0063] Table 2

[0064]

[0065] As can be seen from Table 2 (No. 1 in Table 2 refers to the result of sintering the desulfurized slag after secondary crushing in Example 2), the sulfur content of the desulfurized slag after secondary crushing is 1.6wt%, and when the proportion of returning to sintering is 0.5wt%, the sulfur dioxide concentration at the sintering flue gas outlet is 34.14mg / m 3 Therefore, the desulfurized slag after secondary crushing in Example 2 with the highest sulfur content is used for sintering to meet the ultra-low emission requirements of sintering flue gas, and the desulfurized slag after secondary crushing obtained in the other examples is also used for sintering to meet the ultra-low emission requirements of sintering flue gas.

[0066] Test Example 3

[0067] The particle size analysis of the desulfurized slag after secondary crushing obtained in step (2) of Example 1-6 and Comparative Example 1-2 is shown in Table 3;

[0068] The sintering cup test was used to verify the sintering performance of the desulfurized slag after secondary crushing. The test process parameters are shown in Table 4, the sintering test ratios are shown in Table 5, and the sintering test results are shown in Table 6.

[0069] Table 3

[0070]

[0071]

[0072] Table 4

[0073]

[0074] Table 5

[0075]

[0076] Table 6

[0077]

[0078]

[0079] As can be seen from Table 6, the desulfurized slag after secondary crushing obtained in Examples 1 to 6 is added to the sintering at a ratio of 1.0wt%, which has basically no effect on the performance of the sintered ore, and the valuable elements such as iron and calcium in the desulfurized slag are effectively utilized in the sintering. The desulfurized slag after secondary crushing obtained in Comparative Example 1 cannot be used in sintering due to its large particle size. The desulfurized slag after secondary crushing obtained in Comparative Example 2 is added to the sintering at a ratio of 1.0wt%, and its sintering performance is reduced. The main reason is that the desulfurized slag obtained in Comparative Example 2 has an uneven particle size distribution (as can be seen in Table 3), and the proportion of particles with a particle size of 0.15mm and below reaches 41.46wt%. After being added to the sintering, the permeability of the sintering material layer is poor, thereby affecting the sintering performance.

[0080] In summary, the desulfurized slag obtained after treatment by this scheme can be fully utilized in sintering, which can effectively recover valuable elements such as iron and calcium, and at the same time, the sulfur dioxide emission of the sintering flue gas system meets the national ultra-low emission requirements. The obtained iron particles can all be used in blast furnaces, converters, and electric furnaces. The preparation of S95-grade ore powder from the slag before desulfurization meets the national standard requirements, realizing 100% resource utilization of desulfurized slag, and establishing a good image for the green development of steel enterprises.

[0081] It should be understood that parts not elaborated in detail in this specification belong to the prior art.

[0082] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A KR desulfurization slag resource utilization process, characterized in that: The KR desulfurization slag resource utilization process comprises the following steps: (1) slagging the molten iron to obtain pre-desulfurization slag and molten iron after slagging, granulating and cooling the pre-desulfurization slag and removing iron with a magnetic drum to obtain iron particles and pre-desulfurization slag tailings, returning the iron particles to the blast furnace for utilization, and preparing the pre-desulfurization slag tailings into slag powder; wherein the magnetic field intensity on the surface of the magnetic drum is 1800-2400GS, and the rotation speed is 10-50r / mim; (2) performing KR desulfurization on the molten iron after slagging obtained in step (1), and then performing slagging to obtain desulfurized slag, performing primary crushing and secondary crushing on the desulfurized slag to obtain secondary crushed desulfurized slag, and returning the secondary crushed desulfurized slag to the sintering process for reuse; wherein, in the secondary crushed desulfurized slag, the material with a particle size greater than 5 mm does not exceed 1% of the total weight of the secondary crushed desulfurized slag, and the material with a particle size less than 0.075 mm does not exceed 10% of the total weight of the secondary crushed desulfurized slag.

2. The KR desulfurization slag resource utilization process according to claim 1, characterized in that: In step (1), granulation cooling is performed by the INBA method.

3. The KR desulfurization slag resource utilization process according to claim 1 or 2, characterized in that: In step (1), the content of TFe in the iron particles is ≥85wt%, and the particle size of the iron particles is <120mm.

4. The KR desulfurization slag resource utilization process according to claim 1 or 2, characterized in that: In step (1), the content of MFe in the slag before desulfurization is less than 1wt%.

5. The KR desulfurization slag resource utilization process according to claim 1, characterized in that: In step (1), the slag before desulfurization is dried and ground to a specific surface area greater than 400m 2 / kg, and obtain slag powder.

6. The KR desulfurization slag resource utilization process according to claim 1, characterized in that: In step (2), the desulfurized slag is subjected to primary crushing to obtain primary crushed desulfurized slag, and then the primary crushed desulfurized slag is subjected to secondary crushing to obtain secondary crushed desulfurized slag.

7. The KR desulfurization slag resource utilization process according to claim 6, characterized in that: In step (2), in the desulfurization slag after the primary crushing, the material with a particle size greater than 200 mm does not exceed 10% of the total weight of the desulfurization slag after the primary crushing.

8. The KR desulfurization slag resource utilization process according to claim 6 or 7, characterized in that: In step (2), the temperature of the desulfurized slag after the primary crushing is ≤65°C.

9. The KR desulfurization slag resource utilization process according to claim 1 or 6, characterized in that: In step (2), the primary crushing method is roller crushing.

10. The KR desulfurization slag resource utilization process according to claim 1 or 6, characterized in that: In step (2), the secondary crushing method is hammering or rod milling.

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