Comprehensive utilization method for iron ore

Abstract

The present application relates to the technical field of the comprehensive utilization of resources, and in particular to a comprehensive utilization method for iron ore. The comprehensive utilization method for iron ore comprises the following steps: S1. preparing iron ore into pellets and performing a reduction reaction on the pellets to obtain direct reduced iron; S2. smelting the direct reduced iron to obtain molten slag and molten iron, wherein the content of ferrous oxide in the molten slag is 1 wt% to 4 wt%; and S3. directly hot preparing rock wool from the molten slag online. Different from the prior art, the present application involves the addition of a carbonaceous reducing agent during smelting, reducing the content of ferrous oxide in the obtained molten slag, and improving the thermal insulation performance and tensile mechanical performance of the prepared rock wool, thereby improving the energy-saving effect, durability and safety of the rock wool while increasing the yield of obtained metals, increasing the yield of molten iron, and improving economic benefits.

Description

A comprehensive utilization method for iron ore Technical Field

[0001] This application relates to the field of comprehensive resource utilization technology, specifically to a method for the comprehensive utilization of iron ore. Background Technology

[0002] The iron element in the steel industry mainly comes from iron ore, and the steel production process using iron ore as raw material is primarily based on blast furnace ironmaking. Under the "dual carbon" (carbon diversification) framework, non-blast furnace ironmaking processes, centered on gas-based shaft furnaces, have received more attention and have better development prospects because they eliminate the need for coking and sintering processes, resulting in lower carbon emissions. In recent years, global direct reduced iron (DRI) production has steadily increased. With the continuous development of shaft furnaces and the increasing production of DRI, shaft furnaces will face a situation where they primarily use low- to medium-grade iron ore as raw material.

[0003] After low- and medium-grade iron ore is processed into low- and medium-grade direct reduced iron (DRI) in a shaft furnace, directly feeding it into a steelmaking electric arc furnace or converter, as with high-grade DRI, would result in excessive slag volume, operational difficulties, and high energy consumption due to the need for high-basicity slag to remove elements such as phosphorus and sulfur. This leads to problems such as long smelting cycles and high production costs. Therefore, low- and medium-grade DRI is typically first smelted in a melting electric furnace to produce molten iron and high-temperature melting slag, and then the molten iron is supplied to the steelmaking electric arc furnace or converter for steelmaking. The high-temperature melting slag (approximately 1400-1650℃) is usually cooled by hot pouring or water quenching and then used as cement raw material, resulting in a significant waste of sensible heat and low product added value. Therefore, there is an urgent need to develop a new method for high-value smelting of low- and medium-grade iron ore to improve economic efficiency.

[0004] Rock wool is a man-made fiber with excellent heat insulation, sound absorption, fire resistance, and shock resistance properties. It is widely used in industries such as petroleum, power, metallurgy, and construction, and its price is much higher than cement, resulting in higher added value. Traditional raw materials for rock wool production are diabase and basalt. However, with the increasing scarcity of natural resources and environmental damage caused by mining activities, and in order to reduce production costs, using industrial by-products or waste to produce rock wool has become an important research direction. Traditional slags, such as blast furnace slag, have excessively high alkalinity, making it difficult to directly control their composition within a suitable range for rock wool production. Transporting them to rock wool production workshops or selling them to rock wool manufacturers after cooling results in significant waste of high-temperature slag and its sensible heat. Therefore, there is considerable research on using traditional industrial slags to produce slag wool with higher alkalinity. However, the water resistance, heat resistance, and corrosion resistance of slag wool are far inferior to those of rock wool, resulting in relatively low added value. Patent document CN110818244A discloses a method for directly preparing rock wool using electric furnace smelting of sponge iron slag. This method utilizes electric furnace smelting of sponge iron slag (acidity coefficient greater than 1.5, containing 6-13% FeO) for direct fiberization to produce rock wool. However, this method requires very high-quality sponge iron composition to obtain slag directly usable for rock wool production without the addition of any reducing agents or tempering agents, which is not conducive to industrial-scale production. Furthermore, this scheme uses a smelting electric furnace for melting (i.e., the process of melting and reducing sponge iron in an electric furnace to obtain molten iron and slag). However, the high-temperature melt and arc radiation generated during melting will increase the temperature of the furnace bottom and walls, accelerating the consumption of refractory materials and affecting the service life of the smelting electric furnace. In addition, the thermal insulation and mechanical properties of the rock wool produced using this method need further improvement. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the present invention provides a comprehensive utilization method for iron ore to improve the economic benefits of medium and low grade iron ore, extend the service life of the melting furnace, and further improve the thermal insulation and mechanical properties of the produced rock wool.

[0006] To achieve the above objectives, the solution proposed in this application is as follows:

[0007] This application provides a method for the comprehensive utilization of iron ore, comprising the following steps:

[0008] S1. Iron ore is processed into pellets and then subjected to a reduction reaction to obtain direct reduced iron;

[0009] S2. Mix the carbonaceous reducing agent, the modifier and the direct reduced iron to obtain a mixture, and smelt the mixture to obtain slag and molten iron, wherein the ferrous oxide content of the slag is 1wt%-4wt%.

[0010] S3. The molten slag is directly heated online to produce rock wool.

[0011] Optionally, the comprehensive utilization method of iron ore can be used to process medium and low grade iron ore.

[0012] In this application, medium-low grade iron ore refers to iron ore with TFe < 67 wt%, SiO2 > 3 wt%, Al2O3 > 1 wt%, CaO > 0.3 wt%, and MgO > 0.13 wt%.

[0013] Optionally, in step S1, the reduction reaction is carried out in a gas-based vertical furnace.

[0014] Optionally, in step S2, the smelting is carried out in a melting furnace.

[0015] Optionally, in step S2, the carbonaceous reducing agent, the modifier, and the direct reduced iron are mixed and then smelted.

[0016] Optionally, in step S2, the carbonaceous reducing agent is selected from at least one of coke, pulverized coal, and semi-coke.

[0017] Optionally, the carbonaceous reducing agent in step S2 has a fixed carbon content of 65wt%-85wt%.

[0018] Optionally, in step S2, the amount of the carbonaceous reducing agent is 15-60 kg / t.

[0019] Optionally, in step S2, the amount of the modifier used is 10-50 kg / t.

[0020] Optionally, in step S2, the modifier is selected from lime or a mixture of lime and dolomite.

[0021] Optionally, the quaternary basicity of the slag in step S2 (i.e., the ratio of the mass sum of calcium oxide and magnesium oxide to the mass sum of silicon dioxide and aluminum oxide) is 0.55-0.65.

[0022] Optionally, in the slag obtained in step S2, the content of silicon dioxide is 29.5wt%-60.5wt%, the content of aluminum oxide is 4.5wt%-25.5wt%, the content of calcium oxide is 4.5wt%-30.5wt%, and the content of magnesium oxide is 1.5wt%-15.5wt%.

[0023] Optionally, the smelting process in step S2 is carried out in a smelting device, which is provided with several electrodes for heating. The carbonaceous reducing agent and / or the modifying agent and / or the direct reduced iron are placed around and / or between the electrodes and / or around the inner wall of the smelting device.

[0024] Optionally, in the smelting process described in step S2, the generated slag forms a condensed slag shell on the inner wall of the smelting equipment.

[0025] Optionally, during the smelting process in step S2, when a pile of material is stacked around the inner wall of the smelting equipment, the generated slag forms a condensed slag shell on the inner wall of the smelting equipment. The pile of material is used to block the arc light and reduce the temperature near the furnace wall, so that the temperature of the slag when it comes into contact with the furnace wall is lower than the solidification temperature of the slag, allowing the generated slag to form a condensed slag shell on the inner wall of the smelting equipment.

[0026] Optionally, during the smelting process described in step S2, a layer of condensed iron is formed on the furnace wall and bottom of the smelting equipment.

[0027] Optionally, during the smelting process described in step S2, when the amount of iron remaining at the bottom of the smelting equipment is greater than 500 kg, a temperature gradient will be formed, causing the contact temperature between the molten iron and the furnace wall and bottom to be lower than the solidification temperature of the molten iron, thereby forming a solidified iron layer on the furnace wall and bottom of the smelting equipment.

[0028] Optionally, the stockpile in step S2 includes the direct reduced iron and / or the carbonaceous reducing agent and / or the modifier.

[0029] Optionally, in step S2, the melting temperature is 1400-1650℃.

[0030] Optionally, the comprehensive utilization method of iron ore further includes the following step: refining the molten iron into steel products.

[0031] The beneficial effects of this invention are:

[0032] Unlike existing technologies, this application adds a carbonaceous reducing agent during the smelting process, which reduces the ferrous oxide content in the slag obtained from smelting, improves the thermal insulation performance and tensile mechanical properties of the resulting rock wool, and thus enhances the energy-saving effect, durability and safety of the rock wool.

[0033] This application introduces a carbonaceous reducing agent during the smelting process, which reduces the ferrous oxide content in the slag obtained from smelting, while improving the degree of reduction and the metal yield during smelting, thereby increasing the output of molten iron and improving economic benefits.

[0034] Unlike existing technologies, this application controls the composition of the slag by adding a modifier to keep its basicity at a low level (quaternary basicity of 0.55-0.65), which facilitates the direct preparation of rock wool.

[0035] In the production process using the method of this application, during the smelting process, carbonaceous reducing agent and / or modifier and / or direct reduced iron are placed around and / or between the electrodes of the smelting equipment to form an arc-blocking material pile, so as to accelerate the melting and reaction of the furnace charge. The inner wall of the smelting equipment is provided with a material pile to further block the arc light and reduce the temperature near the furnace wall, so that the temperature of the slag when it comes into contact with the furnace wall is lower than the solidification temperature of the slag. A condensed slag shell is formed on the furnace wall to protect the refractory material from corrosion, thereby extending the service life of the smelting equipment.

[0036] When production is carried out using the method of this application, the amount of iron left at the bottom of the smelting equipment is >500kg. This can create a temperature gradient (specifically, the smelting furnace is heated by electric heating, and its heat source is far away from the furnace wall and bottom. Therefore, the temperature of the upper layer of material near the electrode inside the smelting furnace is higher than that of the lower layer of material far away from the electrode, and the temperature of the furnace wall and bottom is lower than that of the lower layer of material, thus forming a temperature gradient). This makes the contact temperature between the molten iron and the furnace wall and bottom lower than the solidification temperature of the molten iron. A layer of solidified iron is formed on the furnace wall and bottom to protect the refractory material from corrosion, thereby extending the service life of the smelting furnace.

[0037] Unlike existing technologies, this application controls the composition of the slag by adding a modifier to keep its basicity at a low level (quaternary basicity of 0.55-0.65), which facilitates the direct preparation of rock wool.

[0038] This application enables the production of rock wool with excellent thermal insulation and tensile mechanical properties by controlling the amount of modifier within a specific range (10-50 kg / t).

[0039] Unlike existing technologies, this application innovatively uses online tempering in a melting furnace to discharge high-temperature slag, which is then directly used to prepare rock wool while still hot. This maximizes the thermo-mass coupling utilization of the slag and its sensible heat, i.e., using the slag and its residual heat to directly produce rock wool while still hot. This results in high added value for the product, low production cost of rock wool, a simpler and more economical process, and thus improved economic efficiency. At the same time, since the slag in conventional processes is generally post-treated for the production of cement, glass and other products, while its use in rock wool preparation requires the addition of slag conditioners and heating, this application eliminates the post-treatment steps for the slag.

[0040] Compared to traditional technologies that use blast furnaces for production, this application combines gas-based vertical shaft furnaces and electric melting furnaces to process medium and low-grade iron ore, eliminating the coking and sintering processes, and achieving low-carbon production and green energy saving.

[0041] This application addresses the growing shortage of existing high-grade iron ore resources and achieves sustainable development. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0043] Figure 1 is a process flow diagram of the comprehensive utilization method of medium and low grade iron ore in Examples 1-3. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. It should be noted that, unless otherwise specified, in this application, "wt%" refers to mass percentage.

[0045] One embodiment of this application provides a method for the comprehensive utilization of iron ore. This method is used to process medium- and low-grade iron ore and includes the following steps:

[0046] S1. Iron ore is processed into pellets and then subjected to a reduction reaction in a gas-based vertical shaft furnace to obtain direct reduced iron;

[0047] S2. The carbonaceous reducing agent, modifier and direct reduced iron are mixed to obtain a mixture. The mixture is smelted in a melting furnace at a temperature of 1400-1650℃. The melting furnace is equipped with several electrodes for heating. The mixture is placed around and / or between the electrodes and / or around the inner wall of the melting equipment to obtain slag and molten iron. In the slag, the content of silicon dioxide is 29.5wt%-60.5wt%, the content of aluminum oxide is 4.5wt%-25.5wt%, the content of calcium oxide is 4.5wt%-30.5wt%, the content of magnesium oxide is 1.5wt%-15.5wt%, and the content of ferrous oxide is 1wt%-4wt%.

[0048] The carbonaceous reducing agent is selected from at least one of coke, pulverized coal and semi-coke. The amount of carbonaceous reducing agent used is 15-60 kg / t. The fixed carbon content in the carbonaceous reducing agent is 65 wt%-85 wt%.

[0049] The modifier is selected from lime or a mixture of lime and dolomite, and the dosage of the modifier is 10-50 kg / t;

[0050] During the smelting process, when there is a pile of material around the inner wall of the smelting furnace, the generated slag forms a condensed slag shell on the inner wall of the smelting furnace. When the amount of iron left at the bottom of the smelting furnace is greater than 500 kg, the molten iron forms a condensed iron layer on the furnace wall and bottom of the smelting furnace.

[0051] The stockpile includes direct reduced iron and / or carbonaceous reducing agents and / or modifiers;

[0052] S3. The molten slag is directly heated online and then processed into rock wool;

[0053] Molten iron is then processed into steel products.

[0054] Numerous details are explored in the following description to provide a more thorough explanation of embodiments of the invention; however, it will be apparent to those skilled in the art that embodiments of the invention may be practiced without these specific details.

[0055] Example 1

[0056] As shown in Figure 1, this embodiment provides a comprehensive utilization method for medium- and low-grade iron ore, and the specific steps are as follows:

[0057] S1. Medium- and low-grade iron ore (TFe 64.63wt%, SiO2 4.86wt%, Al2O3 1.01wt%, CaO 1.01wt%, MgO 0.15wt%) is processed into pellets. The resulting pellets are placed in a gas-based vertical shaft furnace at a furnace temperature of 900℃. A mixture of carbon monoxide and hydrogen (volume ratio of carbon monoxide to hydrogen is 3:1, and the pressure of the mixture is 0.4MPa) is introduced into the gas-based vertical shaft furnace. The pellets undergo a reduction reaction in the gas-based vertical shaft furnace to obtain direct reduced iron (TFe 87.80wt%, SiO2 6.54wt%, Al2O3 1.36wt%, CaO 1.36wt%, MgO 0.2wt%, metallization rate 93%).

[0058] S2. Add direct reduced iron to a melting furnace, and add 46.45 kg / t carbonaceous reducing agent coke (fixed carbon content of 80.48 wt%) and 24.90 kg / t modifier lime to the melting furnace to obtain a mixture;

[0059] The mixture is smelted at 1560℃. During the smelting process, an arc-damping material pile is formed around and / or between the electrodes and / or around the inner wall of the smelting furnace to accelerate the melting and reaction of the charge. Direct reduced iron, carbonaceous reducing agent coke, and modifier lime are piled around the inner wall of the smelting furnace to further shield the arc and reduce the temperature near the furnace wall. This ensures that the temperature of the slag in contact with the furnace wall is lower than the solidification temperature of the slag, and a condensed slag shell forms on the furnace wall to protect the refractory material from corrosion, thereby extending the service life of the smelting furnace. The amount of iron left at the bottom is 850 kg (that is, after the previous batch of smelting is completed, the mixture formed by the slag and molten iron is not completely discharged, but only part of it is discharged. 850 kg of iron is left at the bottom of the smelting furnace. The mixture formed by the slag and molten iron is left and smelted together with the mixture of the next batch of smelting furnace). This is to form a temperature gradient so that the contact temperature between the molten iron and the furnace wall and bottom is lower than the solidification temperature of the molten iron. A layer of solidified iron is formed on the furnace wall and bottom to protect the refractory material from corrosion, thereby extending the service life of the smelting furnace. 147.25 kg / t of slag (containing 47.96 wt% SiO2, 12.65 wt% Al2O3, 31.94 wt% CaO, 4.42 wt% MgO and 1.0 wt% FeO) and 910 kg / t of molten iron are obtained. During the smelting process, the following reduction reactions mainly occur: FeO+C=Fe+CO (1); SiO2+2C=Si+2CO (2).

[0060] S3. The molten slag is directly guided and spun into fibers while hot to obtain rock wool fibers. The rock wool fibers are then sent to the collection chamber and curing furnace for pressing to obtain 117.8 kg / t rock wool.

[0061] The molten iron is transferred to an electric arc furnace, where it undergoes refining, continuous casting, and rolling processes to obtain 728 kg / t steel billets.

[0062] Example 2

[0063] As shown in Figure 1, this embodiment provides a comprehensive utilization method for medium- and low-grade iron ore, and the specific steps are as follows:

[0064] S1. Medium- and low-grade iron ore (TFe 61.35wt%, SiO2 6.28wt%, Al2O3 1.76wt%, CaO 1.23wt%, MgO 0.61wt%) is processed into pellets. The resulting pellets are placed in a gas-based vertical shaft furnace at a furnace temperature of 900℃. A mixture of carbon monoxide and hydrogen (volume ratio of carbon monoxide to hydrogen is 3:1, and the pressure of the mixture is 0.4MPa) is introduced into the gas-based vertical shaft furnace. The pellets undergo a reduction reaction in the gas-based vertical shaft furnace to obtain direct reduced iron (TFe 81.79wt%, SiO2 8.29wt%, Al2O3 2.32wt%, CaO 1.62wt%, MgO 0.81wt%, metallization rate 93%).

[0065] S2. Add direct reduced iron to a melting furnace, and add 42.77 kg / t carbonaceous reducing agent coke (fixed carbon content of 80.48 wt%) and 40.91 kg / t modifier lime to the melting furnace to obtain a mixture;

[0066] The mixture is smelted at 1550℃. During the smelting process, the mixture forms an arc-blocking material pile around and / or between the electrodes and / or around the inner wall of the smelting furnace. Direct reduced iron, carbonaceous reducing agent coke and modifying agent lime are piled up around the inner wall of the smelting furnace to form a material pile. The amount of iron left at the bottom of the smelting furnace is 800kg. 226.35kg / t of smelting slag (containing 42.81wt% SiO2, 13.78wt% Al2O3, 28.96wt% CaO, 5.0wt% MgO, and 1.0wt% FeO) and 858kg / t of molten iron are obtained. During the smelting process, the following reduction reactions mainly occur: FeO+C=Fe+CO (1); SiO2+2C=Si+2CO (2).

[0067] S3. The molten slag is directly guided and spun into fibers while hot to obtain rock wool fibers. The rock wool fibers are then sent to the collection chamber and curing furnace for pressing to obtain 181.08 kg / t rock wool.

[0068] The molten iron is transferred to a converter for steelmaking, and after refining, continuous casting, rolling and other processes, a 730kg / t steel billet is obtained.

[0069] Example 3

[0070] As shown in Figure 1, this embodiment provides a comprehensive utilization method for medium- and low-grade iron ore, and the specific steps are as follows:

[0071] S1. Medium- and low-grade iron ore (TFe 61.35wt%, SiO2 6.28wt%, Al2O3 1.76wt%, CaO 1.23wt%, MgO 0.61wt%) is processed into pellets. The resulting pellets are placed in a gas-based vertical shaft furnace at a furnace temperature of 900℃. A mixture of carbon monoxide and hydrogen (volume ratio of carbon monoxide to hydrogen is 3:1, and the pressure of the mixture is 0.4MPa) is introduced into the gas-based vertical shaft furnace. The pellets undergo a reduction reaction in the gas-based vertical shaft furnace to obtain direct reduced iron (TFe 81.79wt%, SiO2 8.29wt%, Al2O3 2.32wt%, CaO 1.62wt%, MgO 0.81wt%, metallization rate 93%).

[0072] S2. Add direct reduced iron to a melting furnace, and add 27.62 kg / t carbonaceous reducing agent pulverized coal (fixed carbon content of 75.48 wt%) and 44.42 kg / t modifier lime to the melting furnace to obtain a mixture;

[0073] The mixture was smelted at 1500℃. During the smelting process, the mixture formed an arc-blocking material pile around the electrodes of the smelting furnace and / or between the electrodes and / or the inner wall of the smelting furnace. Direct reduced iron, carbonaceous reducing agent pulverized coal and modifying agent lime were piled up around the inner wall of the smelting furnace to form a material pile. The amount of iron left at the bottom of the smelting furnace was 750 kg. 236.68 kg / t of smelting slag (containing 41.42 wt% SiO2, 12.99 wt% Al2O3, 30.37 wt% CaO, 5.0 wt% MgO and 2.0 wt% FeO) and 843 kg / t of molten iron were obtained. During the smelting process, the following reduction reactions mainly occurred: FeO+C=Fe+CO (1); SiO2+2C=Si+2CO (2).

[0074] S3. The molten slag is directly guided and spun into fibers while hot to obtain rock wool fibers. The rock wool fibers are then sent to the collection chamber and curing furnace for pressing to obtain 201.18 kg / t rock wool.

[0075] The molten iron is transferred to an electric arc furnace, where it undergoes refining, continuous casting, and rolling processes to obtain 717 kg / t steel billets.

[0076] Comparative Example 1

[0077] Except for the following conditions, production was carried out in the same manner as in Example 3:

[0078] S2. Direct reduced iron is added to a melting furnace, and 44.42 kg / t of lime, a modifier, is added to the melting furnace to obtain a mixture;

[0079] The mixture was smelted at 1500℃. During the smelting process, the mixture formed an arc-blocking material pile around and / or between the electrodes of the smelting furnace. Direct reduced iron, carbonaceous reducing agent pulverized coal and modifier lime were piled up around the inner wall of the smelting furnace to form a material pile. The amount of iron left at the bottom of the smelting furnace was 750kg. 252kg / t of smelting slag (containing 41.38wt% SiO2, 11.76wt% Al2O3, 27.68wt% CaO, 4.2wt% MgO and 7.0wt% FeO) and 815kg / t of molten iron were obtained. During the smelting process, the following reduction reactions mainly occurred: FeO+C=Fe+CO (1); SiO2+2C=Si+2CO (2).

[0080] S3. The molten slag is directly guided and spun into fibers while still hot to obtain rock wool fibers. The rock wool fibers are then sent to the collection chamber and curing furnace for pressing to obtain 214.50 kg / t rock wool.

[0081] That is, no carbonaceous reducing agent was added during the smelting process in this comparative example, and the FeO content in the slag obtained from the smelting was 7.0 wt%.

[0082] Comparative Example 2

[0083] Except for the following conditions, production was carried out in the same manner as in Example 3:

[0084] S2. Add direct reduced iron to a melting furnace, and add 27.62 kg / t carbonaceous reducing agent pulverized coal (fixed carbon content of 75.48 wt%) and 60 kg / t modifying agent lime to the melting furnace to obtain a mixture;

[0085] The mixture was smelted at 1510℃. During the smelting process, the mixture formed an arc-blocking material pile around the electrodes of the smelting furnace and / or between the electrodes and / or the inner wall of the smelting furnace. Direct reduced iron, carbonaceous reducing agent pulverized coal and modifying agent lime were piled up around the inner wall of the smelting furnace to form a material pile. The amount of iron left at the bottom of the smelting furnace was 750 kg. 246.67 kg / t of smelting slag (containing 39.87 wt% SiO2, 12.53 wt% Al2O3, 34.97 wt% CaO, 4.3 wt% MgO and 0.5 wt% FeO) and 841.44 kg / t of molten iron were obtained. During the smelting process, the following reduction reactions mainly occurred: FeO+C=Fe+CO (1); SiO2+2C=Si+2CO (2).

[0086] S3. The molten slag is directly guided and spun into fibers while hot to obtain rock wool fibers. The rock wool fibers are then sent to the collection chamber and curing furnace for pressing to obtain 209.67 kg / t rock wool.

[0087] The molten iron is transferred to an electric arc furnace, where it undergoes refining, continuous casting, and rolling processes to obtain 715 kg / t steel billets.

[0088] That is, the amount of modifier added in the comparative smelting process is adjusted to 60 kg / t.

[0089] Performance testing

[0090] The thermal conductivity and compressive strength of the rock wool prepared in Examples 1-3 and Comparative Examples 1-2 were tested, and the results are shown in Table 1.

[0091] The thermal conductivity was tested in accordance with GB / T 10295-2008 Determination of Steady-State Thermal Resistance and Related Properties of Insulation Materials by Heat Flow Meter Method.

[0092] The tensile strength was tested in accordance with GB / T 30804-2014 Determination of tensile strength perpendicular to the surface of thermal insulation products for building.

[0093] Table 1 Test Results

[0094] As shown in Table 1, compared with Comparative Example 1 (ferrous oxide content in the slag is 7.0%), Example 3 (ferrous oxide content in the slag is 2.0 wt%) exhibits a decreased thermal conductivity and increased tensile strength. This result demonstrates that this application improves the thermal insulation and tensile mechanical properties of the prepared rock wool by reducing the ferrous oxide content in the slag obtained from smelting.

[0095] As shown in Table 1, compared with Comparative Example 2 (modifier dosage of 60 kg / t), the thermal conductivity and tensile strength of Example 3 (modifier dosage of 44.42 kg / t) were reduced. This result indicates that by controlling the amount of modifier used during the smelting process within a specific range (10-50 kg / t), this application can produce rock wool with excellent thermal insulation and tensile mechanical properties.

[0096] As shown in Example 3 and Comparative Example 1, compared with Comparative Example 1 (ferrous oxide content in the slag was 6.1%), the iron yield of Example 3 (ferrous oxide content in the slag was 2.0 wt%) increased. This result indicates that by reducing the ferrous oxide content in the slag obtained from smelting and adding a carbonaceous reducing agent during the smelting process, this application can improve the degree of reduction and the metal yield during smelting, thereby increasing the iron yield.

[0097] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for the comprehensive utilization of iron ore, characterized in that, Includes the following steps: S1. Iron ore is processed into pellets and then subjected to a reduction reaction to obtain direct reduced iron; S2. The direct reduced iron is smelted to obtain slag and molten iron, wherein the ferrous oxide content of the slag is 1wt%-4wt%. S3. The molten slag is directly heated online to produce rock wool.

2. The comprehensive utilization method of iron ore as described in claim 1, characterized in that, The comprehensive utilization method is used to process medium- and low-grade iron ore; And / or, in step S1, the reduction reaction is carried out in a gas-based vertical furnace.

3. The comprehensive utilization method of iron ore as described in claim 1, characterized in that, In step S2, the carbonaceous reducing agent, the modifier and the direct reduced iron are mixed and then smelted. And / or, in step S2, the smelting is carried out in a melting furnace; And / or, in the slag obtained in step S2, the content of silicon dioxide is 29.5wt%-60.5wt%, the content of aluminum oxide is 4.5wt%-25.5wt%, the content of calcium oxide is 4.5wt%-30.5wt%, and the content of magnesium oxide is 1.5wt%-15.5wt%.

4. The comprehensive utilization method of iron ore as described in claim 3, characterized in that, In step S2, the carbonaceous reducing agent is selected from at least one of coke, pulverized coal, and semi-coke; And / or, in the carbonaceous reducing agent described in step S2, the carbon content is fixed at 65wt%-85wt%; And / or, in step S2, the amount of the carbonaceous reducing agent is 15-60 kg / t.

5. The comprehensive utilization method of iron ore as described in claim 3, characterized in that, In step S2, the modifier is selected from lime or a mixture of lime and dolomite; And / or, in step S2, the amount of the modifier used is 10-50 kg / t.

6. The comprehensive utilization method of iron ore as described in claim 3, characterized in that, The smelting process described in step S2 is carried out in a smelting device, which is equipped with several electrodes for heating. The carbonaceous reducing agent and / or the modifying agent and / or the direct reduced iron are placed around and / or between the electrodes and / or around the inner wall of the smelting device.

7. The comprehensive utilization method of iron ore as described in claim 3, characterized in that, During the smelting process described in step S2, the generated slag forms a condensed slag shell on the inner wall of the smelting equipment; And / or, during the smelting process described in step S2, molten iron forms a layer of condensed iron on the furnace wall and bottom of the smelting equipment.

8. The comprehensive utilization method of iron ore as described in claim 7, characterized in that, During the smelting process described in step S2, when a pile of material is stacked around the inner wall of the smelting equipment, the generated slag forms a condensed slag shell on the inner wall of the smelting equipment. And / or, during the smelting process described in step S2, when the amount of iron remaining at the bottom of the smelting equipment is greater than 500 kg, a layer of condensed iron is formed on the furnace wall and bottom of the smelting equipment.

9. The comprehensive utilization method of iron ore as described in claim 8, characterized in that, The stockpile in step S2 includes the direct reduced iron and / or the carbonaceous reducing agent and / or the modifier.

10. The method for comprehensive utilization of iron ore as described in claim 1, characterized in that, It also includes the following steps: The molten iron is then refined into steel products.

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