A hot pressing method for finished products and iron-containing cold materials produced by a rotary hearth furnace

Abstract

The present invention discloses a method for hot pressing the finished product and ferrous cold material produced in a rotary hearth furnace. The method comprises the following steps: uniformly mixing the ferrous cold material with the high-temperature finished product produced in the rotary hearth furnace; feeding the high-temperature mixed material into a hot pressing process for hot pressing; and screening the hot-pressed mixed material using a vibrating screen, followed by classified disposal after screening. The method utilizes the sensible heat of the high-temperature finished product produced in the rotary hearth furnace to heat the ferrous cold material at room temperature. By utilizing the complementarity of the disposal methods, the two materials are comprehensively utilized, making the disposal process more rational, reducing carbon emissions to the environment, saving resources, and reducing costs.

Description

Technical Field

[0001] The present invention relates to the technical field of iron and steel metallurgy, and more particularly to a method for hot pressing finished products and iron-containing cold materials produced in a rotary hearth furnace. Background Art

[0002] During the production process of steel enterprises, a large amount of metallurgical dust and sludge is generated. These metallurgical dust and sludge usually contain elements such as iron and zinc. However, due to the high iron and zinc content, they cannot be directly reused in the steelmaking process. Therefore, they need to be rationally disposed of. With the rapid development of rotary hearth furnace technology, the rational disposal of metallurgical dust and sludge has been realized. The finished products produced by the rotary hearth furnace, such as metallized pellets and undersize powder, are all at a relatively high temperature and contain a high level of metallic iron. The high-iron-content materials can be recycled and supplied to blast furnaces and steelmaking, which can achieve resource recycling to a certain extent. At present, the disposal method for high-temperature finished products such as metallized pellets and undersize powder is usually to put them into a cylindrical cooler, cool them, and then screen, collect and transport them. However, they still need to be heated again for subsequent use, and a large amount of binder needs to be added during the pressing process of the cooled material. This disposal method not only has a general pressing effect on high-temperature finished products, but also the strength of the pressed pellets is not high.

[0003] For the iron-containing cold materials produced in the steel metallurgical process, they often need to be heated and then sent to steel mills for subsequent use, so as to achieve resource recycling. The conventional processing process for iron-containing cold materials is to use a rotary kiln to heat them to 800°C and then send them to steel mills for subsequent use. However, this disposal method makes the production process more cumbersome and lengthy, wasting a lot of time, and on the other hand, it requires a lot of fuel consumption, resulting in unnecessary waste.

[0004] At present, there are relevant literature reports on methods for hot pressing high-temperature finished products produced by rotary hearth furnaces. The literature with publication number CN215628198U "A hot pressing and hot delivery steelmaking system for metallized pellets in a rotary hearth furnace" reports a method for hot pressing high-temperature finished products in a rotary hearth furnace. The literature proposes that the high-temperature products produced at the output end of the rotary hearth furnace are directly hot pressed and then hot delivered to the steelmaking system, which can achieve maximum energy conservation and emission reduction for subsequent steelmaking processes and further reduce operating costs. The compact structure of the hot pressed blocks can avoid contact between the internal metal and the air to the greatest extent, reducing the occurrence of oxidation reactions. However, the processing method of the literature will produce a large amount of black smoke during the production process, causing certain pollution to the air environment. In addition, the higher material temperature generated by the metallized pellets is not fully utilized, exceeding the temperature required for the hot pressed blocks, resulting in excess heat and, to a certain extent, causing waste heat loss. Therefore, in order to further optimize the process of the rotary hearth furnace disposal method, a hot pressing disposal method for finished products and iron-containing cold materials produced by a rotary hearth furnace is proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide a hot pressing treatment method for finished products and iron-containing cold materials produced in a rotary hearth furnace, so as to solve the problem of heat loss in the treatment process of high-temperature finished products produced in a rotary hearth furnace in the prior art, the problem of environmental pollution caused during the production process, and the technical problem that the conventional treatment process of iron-containing cold materials is a complex process of heating through a rotary kiln and consumes a large amount of fuel. The high-temperature sensible heat of the finished products produced in the rotary hearth furnace is used to heat the low-temperature iron-containing cold materials, and the complementarity of the treatment methods is utilized to comprehensively utilize the two materials, make the treatment process more rational, reduce carbon emissions to the environment, save resources, and reduce costs.

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

[0007] The present invention provides a method for hot pressing finished products and iron-containing cold materials produced in a rotary hearth furnace, comprising the following steps:

[0008] S1. Mix the iron-containing cold material with the high-temperature finished product produced in the rotary hearth furnace;

[0009] S2. The mixture obtained in step S1 at a high temperature is fed into a hot pressing process for hot pressing;

[0010] S3. The hot-pressed mixed material is screened using a vibrating screen and then classified for disposal.

[0011] As one aspect of a hot pressing method for a rotary hearth furnace produced finished product and iron-containing cold material, S1 comprises the following steps:

[0012] S11. The high-temperature finished product produced in a rotary hearth furnace at a temperature of 1100 ℃ is used as a heat source. The high-temperature finished product has an iron content of 60 to 70%, a zinc content of 0.3 to 1%, and a metallization rate of 65 to 80%;

[0013] S12. Select iron-containing cold material at room temperature as the material to be heated, the iron-containing cold material has an iron content of 80 to 95% and a moisture content of ≤5%;

[0014] S13. The high-temperature finished product produced by the rotary hearth furnace and the iron-containing cold material are uniformly mixed by a mixing machine, and the average temperature of the mixed material in the mixing machine is controlled to reach 700 to 800°C, and the iron content of the mixed material is ≥70%.

[0015] As one aspect of a method for hot pressing treatment of finished products and iron-containing cold materials produced in a rotary hearth furnace, in step S13, during the mixing process of the high-temperature finished products and the iron-containing cold materials produced in the rotary hearth furnace, a rotary mixing drum or other mixing machine is used for mixing, and an industrial temperature sensor is used for real-time temperature measurement, while the addition ratio of the two materials is controlled so that the temperature of the mixed material reaches the average temperature.

[0016] As one aspect of the hot pressing treatment method for finished products and iron-containing cold materials produced in a rotary hearth furnace, the iron content of the mixed material in S13 is detected by XPS or XRD method.

[0017] As one aspect of the hot pressing treatment method for finished products and iron-containing cold materials produced in a rotary hearth furnace, the hot press used in the hot pressing process in S2 is a hydraulically driven punch press or a double-roll briquetting machine, the hot pressing temperature is 700-800°C, the pressing pressure is set at 10-24 MPa, and the pressing time is 0.1-20s / piece.

[0018] As one aspect of a hot pressing method for a rotary hearth furnace produced finished product and iron-containing cold material, S3 comprises the following steps:

[0019] S31. The hot-pressed mixture is sieved using a vibrating screen to separate the mixed material into blocks and powders;

[0020] S32. The oversize material from the vibrating screen is directly hot loaded or cooled in a cooling process and then sent to a converter or blast furnace for use;

[0021] S33. The undersize material of the vibrating screen is returned to step S1 for recycling.

[0022] As one aspect of the hot pressing treatment method for finished products and iron-containing cold materials produced in a rotary hearth furnace, the screening size of the vibrating screen in S31 is 5 mm.

[0023] As one aspect of a hot pressing treatment method for finished products and iron-containing cold materials produced in a rotary hearth furnace, in S32, the zinc content of the oversize material after cooling through the cooling process is less than 1%, the iron content is 70-85%, and the metallization rate is ≥70%.

[0024] By adopting the above technical solution, the present invention has the following advantages:

[0025] The present invention provides a hot pressing treatment method for finished products produced by a rotary hearth furnace and iron-containing cold materials. The finished products produced by the rotary hearth furnace still have a high temperature of 1100°C. The sensible heat of the high-temperature material is used to heat other iron-containing cold materials that need to be heated, thereby saving the process and energy consumption required for heating the cold materials and reasonably recycling and utilizing the waste heat of the high-temperature materials. The materials after the finished products produced by the rotary hearth furnace and the iron-containing cold materials are evenly mixed still have a relatively high temperature and can be directly hot pressed, thereby saving the process of cooling and then heating in a cylindrical cooler in the traditional treatment process of the finished products produced by the rotary hearth furnace, thereby saving time and energy costs. The mixed materials of the finished products produced by the rotary hearth furnace and the iron-containing cold materials are hot pressed without the need to add a large amount of additional binder, and the hot-pressed blocks after hot pressing have high strength, thereby saving the capital cost of the binder. The iron content in the hot-pressed products is above 70%, thereby realizing the reuse of resources. No obvious pollutants such as black smoke are generated during the production process, thereby reducing environmental carbon emissions and being environmentally friendly to a certain extent. The present invention provides a hot pressing treatment method for finished products and iron-containing cold materials produced in a rotary hearth furnace, which effectively improves production efficiency, eliminates the process of repeated heating of materials, reduces heat loss, and saves time and energy costs; it can rationally utilize elements such as iron and zinc in products produced in the rotary hearth furnace, improve the recovery rate, reduce safety hazards, and reduce the degree of pollution to the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Other features, objects and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings.

[0027] Figure 1 This is a flow chart of the hot pressing treatment method of the rotary hearth furnace production finished product and iron-containing cold material of the present invention;

[0028] Figure 2 This is a flow chart of uniformly mixing the iron-containing cold material with the finished product produced in the rotary hearth furnace of the present invention;

[0029] Figure 3 This is a flow chart of screening and classifying the hot-pressed mixed material according to the present invention. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is described in detail below in conjunction with the drawings of the specification. The detailed features and advantages of the present invention are described in detail in the specific implementation mode. The content is sufficient to enable any technical personnel in this field to understand the technical content of the present invention and implement it accordingly. According to the description, claims and drawings disclosed in this specification, those skilled in the art can easily understand the relevant purposes and advantages of the present invention.

[0031] Since cold iron-containing materials still need to be heated to 700-800°C in a rotary kiln before hot pressing during normal use, while finished products produced in a rotary hearth furnace need to be cooled in a drum cooler before use, the complementary nature of these two material handling methods can be exploited to mix the two materials, eliminating the need for heating and cooling each other, achieving heat recovery and reducing unnecessary cumbersome processes, thereby further optimizing the production system.

[0032] Figure 1 The flow chart of the hot pressing treatment of the finished product and the iron-containing cold material produced by the rotary hearth furnace of the present invention is shown. A hot pressing treatment method of the finished product and the iron-containing cold material produced by the rotary hearth furnace includes the following steps: Figure 1 As shown:

[0033] S1. Mix the iron-containing cold material with the high-temperature finished product produced in the rotary hearth furnace;

[0034] Figure 2 It shows a flow chart of uniformly mixing the iron-containing cold material with the finished product produced in the rotary hearth furnace according to the present invention;

[0035] Among them, S1 includes the following steps: Figure 2 As shown:

[0036] S11. The high-temperature product produced in a rotary hearth furnace at a temperature of 1100 ℃ is used as a heat source. The high-temperature finished product has an iron content of 60 to 70%, a zinc content of 0.3 to 1%, and a metallization rate of 65 to 80%;

[0037] S12. Select cold iron-containing material at room temperature (i.e., temperature of about 25°C) as the material to be heated, with an iron content of 80-95% and a moisture content of ≤5%;

[0038] S13. The iron-containing cold material at room temperature is mixed evenly with the high-temperature finished product produced in the rotary hearth furnace through a rotary mixing drum or other mixing machinery. The sensible heat of 1100°C of the high-temperature finished product of the rotary hearth furnace is used as a heat source to heat and mix the external iron-containing cold material. During the mixing process of the two materials, real-time temperature measurement is performed using temperature measuring equipment such as industrial temperature sensors. At the same time, the addition ratio of the two materials is controlled, and the average temperature of the materials in the mixing machinery is controlled to be between 700 and 800°C. The two materials are mixed evenly, and the iron content of the mixed material is controlled to be greater than or equal to 70%. The iron content of the mixed material can be detected by sampling and methods such as XPS or XRD.

[0039] S2. The hot mixed material is sent to the hot pressing process for hot pressing. The hot press used is a hydraulically driven punch press or a double-roll briquetting machine. The hot pressing temperature is 700-800°C, the pressing pressure is set at 10-24 MPa, and the pressing time is 0.1-20 seconds per block. Because the metal contained in the mixed material has good plasticity at high temperature, it is not necessary to add a large amount of binder. The hot pressed blocks not only have high compressive strength but are also not easy to break.

[0040] Figure 3 The flow chart shows the screening and classification of the mixed material after hot pressing.

[0041] S3. The hot-pressed mixed material is screened using a vibrating screen and then classified for disposal.

[0042] S3 includes the following steps: Figure 3 As shown:

[0043] S31. The hot-pressed mixed material is screened using a vibrating screen with a screening size of 5 mm to separate the lumps and powders of the mixed material. The lumps remaining on the vibrating screen are called oversize, and the powder remaining below the vibrating screen is called undersize.

[0044] S32. The oversize material from the vibrating screen can be directly hot-charged or cooled in a cooling process, depending on demand, before being sent to an electric furnace, converter, or blast furnace. Hot-charging reduces the need for reheating in the steel mill, reducing carbon emissions while saving significant energy and capital costs, making it more environmentally friendly. After cooling, the hot-pressed briquettes have a zinc content of less than 1%, an iron content of 70-85%, a metallization ratio of ≥70%, and are resistant to breakage, enabling comprehensive utilization of raw materials.

[0045] S33. The undersize material of the vibrating screen is returned to the cold material and hot material mixing process in step S1 for recycling.

[0046] The following Examples 1-3 take a 200,000-ton rotary hearth furnace project and a 60,000-ton steel slag magnetic separation particle steel hot briquetting project as examples. The 200,000-ton rotary hearth furnace project has an annual DRI output of 140,000 tons. The 1100°C hot DRI is indirectly water-cooled for steelmaking use. The total iron content of the finished pellets of the rotary hearth furnace is 60-70%, the zinc content is 0.3-1%, and the metallization rate is 65-80%. The 60,000-ton steel slag magnetic separation particle steel hot briquetting project uses gas heating with an energy consumption of 0.9 GJ (30.76 kgce) per ton. The iron content of the steel slag magnetic separation particle steel is 80-95%, and the moisture content is ≤5%.

[0047] Example 1

[0048] In this embodiment, the rotary hearth furnace project and the steel slag magnetic separation particle steel hot pressing briquetting project are built together, and the heating system of the particle steel is eliminated. The hot pressing treatment method of the rotary hearth furnace production product and the iron-containing cold material is as follows:

[0049] The finished pellets from the rotary hearth furnace and the magnetically separated steel particles at room temperature are mixed evenly in a rotary mixing drum. The sensible heat of 1100°C from the high-temperature finished pellets produced by the rotary hearth furnace is used as a heat source to heat and mix the magnetically separated steel particles. During the mixing process, an industrial temperature sensor is used to measure the temperature in real time and control the addition ratio of the two materials. The average temperature of the materials in the rotary mixing drum is controlled at 750°C. The two materials are mixed evenly and the iron content of the mixed material is 75%. Subsequently, the hot mixture is sent to the hot pressing process for hot pressing. The hot press is a hydraulically driven punch press with a hot pressing temperature of 700°C, a pressing pressure set at 10MPa, a roller speed of 7r / min, and a pressing time of 10s per piece. Finally, the hot-pressed mixture is screened using a vibrating screen to separate the lumps and powders. The oversize material is directly hot-charged and sent to the converter or blast furnace for use. The oversize material has a zinc content of 0.9%, an iron content of 75%, and a metallization rate of 80%. The undersize material is returned to the mixing process for recycling.

[0050] This embodiment can reduce project investment by approximately RMB 20 million, and can save energy by up to 1845.6 tce per year, thus achieving good energy-saving and carbon-reduction effects.

[0051] Example 2

[0052] The hot pressing method for the finished product and the iron-containing cold material produced by the rotary hearth furnace in this embodiment is as follows:

[0053] The high-temperature finished ball powder produced by the rotary hearth furnace and the steel slag magnetic separation particle steel at room temperature will be mixed evenly through a rotary mixing drum. The sensible heat of 1100℃ of the finished ball powder of the rotary hearth furnace is used as a heat source to heat and mix the steel slag magnetic separation particle steel. During the mixing process, an industrial temperature sensor is used to measure the temperature in real time, and the addition ratio of the two materials is controlled. The average temperature of the materials in the rotary mixing drum is controlled at 780℃. The two materials are mixed evenly. The iron content of the mixed material is 80%. Subsequently, the high-temperature mixed material is sent to the hot pressing process for hot pressing. The hot press is a double-roll briquetting machine with a hot pressing temperature of 750℃, a pressing pressure set at 17MPa, a double-roll speed of 9r / min, and a pressing time of 0.28s / piece. Finally, the hot-pressed mixture is screened using a vibrating screen to separate the blocks and powders. The oversize material is directly cooled in the cooling process and sent to the converter or blast furnace for use. The zinc content of the oversize material is 0.7%, the iron content is 80%, and the metallization rate is 85%. The undersize material is returned to the mixing process for recycling.

[0054] Example 3

[0055] The hot pressing method for the finished product and the iron-containing cold material produced by the rotary hearth furnace in this embodiment is as follows:

[0056] The high-temperature finished ball powder produced by the rotary hearth furnace and the steel slag magnetic separation particle steel at room temperature will be mixed evenly through a rotary mixing drum. The sensible heat of 1100℃ of the finished ball powder of the rotary hearth furnace is used as a heat source to heat and mix the steel slag magnetic separation particle steel. During the mixing process, an industrial temperature sensor is used to measure the temperature in real time, and the addition ratio of the two materials is controlled. The average temperature of the materials in the rotary mixing drum is controlled at 800℃. The two materials are mixed evenly. The iron content of the mixed material is 85%. Subsequently, the high-temperature mixed material is sent to the hot pressing process for hot pressing. The hot press is a double-roll briquetting machine with a hot pressing temperature of 760℃, a pressing pressure set at 24MPa, a double-roll speed of 6r / min, and a pressing time of 0.42s / piece. Finally, the hot-pressed mixture is screened with a vibrating screen to separate the blocks and powders. The oversize material is directly cooled in the cooling process and sent to the converter or blast furnace for use. The zinc content of the oversize material is 0.5%, the iron content is 85%, and the metallization rate is 88%. The undersize material is returned to the mixing process for recycling.

[0057] Finally, it should be pointed out that although the present invention has been described with reference to the current specific embodiments, ordinary technicians in this technical field should realize that the above embodiments are only used to illustrate the present invention and are not used to limit the present invention. Various equivalent changes or substitutions can be made without departing from the concept of the present invention. Therefore, as long as the changes and modifications to the above embodiments are within the scope of the essential spirit of the present invention, they will fall within the scope of the claims of the present invention.

Claims

1. A method for hot pressing finished products and iron-containing cold materials produced in a rotary hearth furnace, characterized in that: The following steps are involved: S1. Evenly mixing the iron-containing cold material with the high-temperature finished product produced in the rotary hearth furnace, including the following steps: S11. The high-temperature finished product produced in a rotary hearth furnace at a temperature of 1100 ℃ is used as a heat source. The high-temperature finished product has an iron content of 60 to 70%, a zinc content of 0.3 to 1%, and a metallization rate of 65 to 80%; S12. Select iron-containing cold material at room temperature as the material to be heated, the iron-containing cold material has an iron content of 80 to 95% and a moisture content of ≤5%; S13. The high-temperature finished product and the iron-containing cold material produced by the rotary hearth furnace are uniformly mixed by a mixing machine, and the average temperature of the mixed material within the mixing machine is controlled to reach 700 to 800 ℃. During the mixing process of the high-temperature finished product and the iron-containing cold material produced by the rotary hearth furnace, a rotary mixing drum or other mixing machine is used for mixing, and an industrial temperature sensor is used to measure the temperature in real time, while controlling the addition ratio of the two materials so that the temperature of the mixed material reaches the average temperature; S2. The mixture obtained in step S1 at a high temperature is sent to a hot pressing process for hot pressing. The hot press used in the hot pressing process in S2 is a hydraulically driven punch press or a roller briquetting machine, the hot pressing temperature is 700-800°C, the pressing pressure is set to 10-24 MPa, and the pressing time is 0.1-20 seconds per block; S3. The hot-pressed mixed material is screened using a vibrating screen, and the screening is followed by classification and disposal, comprising the following steps: S31. The hot-pressed mixture is sieved using a vibrating screen to separate the mixed material into blocks and powders; S32. The oversize material from the vibrating screen is directly hot loaded or cooled in a cooling process and then sent to a converter or blast furnace for use; In said S32, the zinc content of the above-mentioned material after cooling by the cooling process is less than 1%, the iron content is 70-85%, and the metallization rate is ≥70%; S33. The undersize material of the vibrating screen is returned to step S1 for recycling.

2. The hot pressing method for the finished product and the iron-containing cold material produced by the rotary hearth furnace according to claim 1, characterized in that: The iron content of the mixed material is ≥70%.

3. The hot pressing treatment method for finished products and iron-containing cold materials produced by a rotary hearth furnace according to claim 1, wherein the iron content of the mixed material in S13 is detected by XPS or XRD method.

4. The hot pressing method for the finished product and the iron-containing cold material produced by the rotary hearth furnace according to claim 1, characterized in that: The screening size of the vibrating screen in S31 is 5 mm.

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